Chapter 9. Woody Ornamentals. Learning Objectives

Transcription

1 Chapter 9 Woody Ornamentals Learning Objectives 1. Explain how to use a dichotomous key by recognizing different morphological characteristics to identify woody ornamentals 2. Select the best woody ornamentals for a landscape based on site, use and plant characteristics 3. Describe the steps in transplanting a woody ornamental 4. Demonstrate the proper way and times to prune woody ornamentals 5. Identify a stressed tree and the various site problems for urban trees

2 Woody Ornamentals Woody plants provide many important resources for our daily functions. Woody plants fix CO2, provide materials buildings and paper products, and provide comfort and beauty to our landscapes. Because woody plants are so functional, it makes sense that they make up a significant portion of our landscapes and play a distinct role in the aesthetics of urban spaces. These plants lend background, structure and scale to our aesthetic view. Tress, shrubs, vines and groundcovers are all considered woody ornamentals. Woody plants grow differently than herbaceous plants. Therefore, it is important to know how to care for existing trees as well as how to establish new plants. When choosing to plant a new tree or shrub, the investment in time and expense is well worth the effort. Similarly, caring for existing woody ornamentals, which are difficult and timely to replace, is just as important. Tree Identification Trees come in a variety of shapes, sizes and colors. Even closely related trees may have fascinating differences in: leaf shape, leaf color, bark texture and flowers. A glance at any tree guide will reveal a dozen very different trees that are generally referred to as oak or pine. Much confusion can be avoided by learning to talk about trees using their botanical names. Although many people are intimidated by the Latin terms used in botanical naming, identifying trees is a logical, orderly process. It can be successfully accomplished with a reliable field guide and a little practice. Scientific Names A plant s name represents the genus and species group to which it belongs. Woody ornamentals within the same genus (pl. genera) will have many strong similarities. Plants may cross-pollinate within their species, but not with other genera. Hybrid trees have been deliberately or naturally bred by cross-pollination between two species within one genus. Following the binomial naming system, a tree may be identified as Acer rubrum ( the maple that is red ) or Acer saccharum ( the maple that produces sugary sap ). Species names may describe a specific characteristic of the tree, describe where it was first discovered or list who discovered it. Not all species names directly relate to the commonly known name as clearly as the examples above. For comparison, the Norway maple is correctly identified as Acer platanoides, referring not to Norway, but to how its leaves resemble those of sycamore (platanoides: like Platanus ). Using an Identification Key One of the most important steps in identifying a tree is learning to use a reputable field guide. Most guides rely on a simple keying system through which characteristics that most closely describe the tree are chosen. A full botanical key is referred to as a dichotomous key, meaning that the reader is continually making either/or choices. Each point in the key will require a selection from two optional characteristics. The first step may be to choose whether the tree has needles or broad leaves. From there, continuous step-by-step choices are made based on the tree s morphology. Characteristics compared usually include leaf shape and placement, bud shape and placement, fruit and bark type, flowers, and the tree s habit, which includes where and how it grows naturally. Within every species, there will sometimes be trees that show natural variations. Growing conditions affect tree size and shape. Therefore, environmental effects always need to be considered when attempting to assess adult tree size. Lack of root growth or inadequate water and nutrients will stunt leaf, trunk and canopy growth in trees. Although leaf identification is one way to begin differentiating trees, learning to identify other characteristics is important as well. This information will be necessary if trying to identify a tree after the leaves of deciduous trees have fallen. Some reliable, year-round identification characteristics include the texture, pattern and color of the bark and the shape and arrangement of buds on twigs. Tennessee Master Gardener Handbook 220

3 Figure 1. Leaf arrangements: Opposite, Whorled, and Alternate Leaf Identification Leaves occur in each tree species in specific, recognizable patterns. Leaves may be simple or compound, or they may grow singly. Additionally, the leaves may be made up of a number of smaller leaflets. The arrangement of leaves is also an important step for identification. For example, leaves can be opposite, whorled or alternate. Opposite and whorled leaves come from the same node, and alternate leaves come from separate nodes and the direction of leaf growth on each node changes from the previous node. Leaf edges are also commonly used for general identification. Leaves with smooth, unbroken edges are entire. Other types may show either wavy or undulate edges, or a variety of cut edges that make lobed, serrate or dentate points. Leaf identification on trees with needle-type foliage is made from the shape of the needles and the number and arrangement of the needles in bundles. Figure 2. Samara of a Red Maple as cones, nuts or fruit, depending on the type fruiting occurs. Plant Groups Woody ornamentals may be either gymnosperms (gymnos = naked, sperm = seed) or angiosperms (angeion = vessel, sperm = seed). Gymnosperms, which include the conifers and ginkgos, are more primitive than angiosperms. They generally have unshowy flowers with open parts that are adapted to wind pollination. Gymnosperms produce seeds that are exposed between the scales of cones, thus they are often referred to as conifers. In contrast, wind, insects, birds or other animals can pollinate angiosperms. As such, angiosperms have flowers that secrete nectar, which attracts the pollinators. Angiosperms produce covered seeds, like nuts or fruits, are angiosperms. Reproduction Woody ornamentals can be propagated both naturally and artificially. Trees may be sexually reproduced by germinating seeds or asexually reproduced by rooting cuttings, grafting or layering. Trees, shrubs and groundcovers are flowering plants that can be fertilized through pollination. During pollination, pollen grains containing sperm are deposited onto the female parts of the flowers. The fertilized ovum forms seeds, which are commonly recognized of tree. Most trees, like maples with their double-winged samaras, have very distinctive seed shapes. Depending upon the species, trees may be monoecious, which means they produce male flowers and female flowers on the same tree or dioecious, which means that male flowers and female flowers are produced on separate trees. In dioecious species, the female trees produce the seeds, or the fruit. In some cases, as with gingko (Gingko biloba) trees, planting male trees avoids the unpleasant smelling fruit. Unfortunately, determining the sex of monoecious trees is rarely possible until flowering and When conditions are not optimal for fruiting, flowering or seed germination, plants can be propagated by asexually. Asexually propagation is also useful if plants are not strong genetic seed producers or if the traits or characteristics desired are not true when repro- duced from seed, as in a cultivar. For more information on plant propagation, see Chapter 6, Plant Propagation. Tennessee Master Gardener Handbook 221

4 Figure 3. Maintained English Ivy used as Groundcover Categories of Woody Ornamentals Woody ornamental plants are placed in four categories: vines, groundcovers, shrubs and trees. offer diverse visual qualities and are valued for Vines Vines are climbing or crawling woody plants without self-supporting, upright stems. Vines their rich texture, foliage color and growth habit. Vines are segregated into three general groups, depending on climbing characteristics. Vines like Boston ivy climb by attaching small root-like holdfasts to a wall as a means of support. These may be modified with tendrils with such as like English ivy, have small rootlets small circular discs at the tips. Other vines, along the stem that firmly attach to either brick or wood. The second group of vines, such as clematis and grape, climb by attaching and winding tendrils, leaf-like appendages that act as tendrils, around the object that they are growing on. The third group of vines, including bittersweet and wisteria, climb by twining. Vines twine in different directions. For instance, Chinese wisteria twines and climbs counterclockwise, while Japanese wisteria twines and climbs clockwise. Most vines can become a tangled mass of foliage on the ground if they are not sup- ported properly. Wooden structures, such as fences and arbors, are often damaged due to the climbing aspects of vines. Vines need structures that are strong enough to support their vigorous growth. By knowing in advance how each vine climbs, the proper means of support can be selected. However, be careful which structures are chosen to support the vines. Vines that use houses for support often provide carpenter ants an entry point into the structure. Pruning vines is necessary to remove old wood. Several cuts may be required for each stem so that they can be untangled. Pruning is also necessary to provide a neat appearance. Groundcovers Groundcovers are plants that grow up to 18-inches tall and that cover the ground. Groundcovers include turf, low spreading shrubs, creeping plants and prostrate vines. Typically, turf is excluded from the list because most ground covers can be damaged if exposed to foot traffic. Groundcovers are beneficial in the landscape because they can: Help control erosion Control foot traffic without impeding the view Reduce lawn maintenance Grow in areas, such as deep shade, where lawn turf cannot Fill narrow and odd-shaped areas where mowing and edging is difficult Conserve soil moisture and lower soil temperatures during periods of extreme heat Groundcovers are installed as small plants and require a considerable amount of maintenance during the first few years. Weed control in a newly planted bed can be difficult and expensive. Most groundcovers take about 3 years to become established. An old saying about English ivy is the first year it sleeps, the second year it creeps and the third year it leaps. Fertility and irrigation practices can encourage vigorous growth; however, if cultural practices are poor, then the groundcovers will be disappointing. (See Tables at end of chapter). Tennessee Master Gardener Handbook 222

5 Figure 4. Tree Forms: Weeping, Full- Crowned, Columnar, Spreading. Figure 5A. Bark of a Crape Myrtle Shrubs Shrubs are woody plants that reach heights of 12 to 15 feet and can often be as wide. Most shrubs can be pruned, but as they mature, width and height is important in planning a landscape. They may be single stem or multi-stem with foliage extending nearly to the ground. Common shrub forms are lowspreading (junipers), round or upright (the majority of shrubs fall into this form), vase (spirea, forsythia), pyramidal (arborvitae) and columnar (upright junipers). will create maintenance problems should be Trees Knowing a tree s mature size, habit and characteristics is helpful in planning a landscape design, especially if you need to plant under or near utility lines or in confined areas. Trees are considered woody plants that grow more than 15-feet tall and commonly have a single trunk. A typical nursery practice is to develop a multi-trunk tree by pruning the trees at a young age. Tree canopies are grouped into round or oval (sugar maple), vase (elms), pendulous or weeping (willow, cherry), pyramidal (spruce, fir, hemlock) and columnar (Lombardy poplar). Selection and Uses of Woody Ornamentals There are two common methods of selecting plants. One method is to select the plant first and then find a suitable site. The other method is to select a site first and, based on that site s characteristics, select a suitable plant. The methods differ in that the first method primarily considers the aesthetics of the plant. These aesthetics include the shape, size, form and color of the plant and it s leaves, bark and flowers. The second method considers many cultural aspects. These aspects include plant hardiness, soil type, sun exposure, temperature fluctuations, soil drainage, and existing structures, hardscapes or other plant material. Regardless of which method is used, in most situations, the bottom line is how aesthetic the plant appears in the landscape. Site Considerations Consider the various site conditions of a place before planting a tree. Determine if the tree will tolerate the site s soil and drainage capabilities, climate and microclimate, moisture, and light. Next, verify that the ornamental will fit in the space at maturity. Plants with undesirable characteristics that avoided. These problems include vigorous root systems, prolific seeds, long-term leaf drop and pest issues. Planting trees and shrubs that are appropriate for the site will ensure that the landscaping will develop quickly into an asset. Tennessee Master Gardener Handbook 223

6 Figure 5B. Pink Flowering Dogwood Site Evaluation Figure 5C. Variegated Kousa Dogwood Figure 5D. American Beautyberry Uses Consider the items below when evaluating a potential site: The scale drawing: Complete a scale drawing of the potential site. A good measure to use is 1 inch on the drawing equals 25 feet of the site. Include a north arrow for orientation Location: Note location of existing buildings, streets, sidewalks and other hardscapes Other plantings: Note location of other trees and other landscape Utilities: Note location of overhead and underground utilities* Problems: Be aware of known problems such as areas of poor drainage or construction fill Accessibility: Examine access to the site Undesirable areas: Examine sources of undesirable view or noise for screening plantings Plants can be used for various purposes in the landscape. In design, a group of woody plants can be used to create a screen for limiting a view or for creating a boarder. Tree lines can also be used for windbreaks and shade. Deciduous trees can shade the southeast side of a house in the summer and provide light and allow light to heat the house in the winter. Shrubs and groundcovers are often used as foundation plants around the home to soften the hardscape. Woody ornamentals also provide functional solutions, such as erosion control on slopes, and lend aesthetic shape, texture and color to a landscape. For more information on landscape design, see Chapter 15, Landscape Design. Containers and Patios Containerized trees and shrubs provide a permanent structure to the container garden design. Patio, decks, entrances, courtyards and other small areas can be landscaped with the use of small trees, shrubs, groundcovers Tennessee Master Gardener Handbook 224

7 Figure 5E. Mass of Flowers on Sweet Autumn Clematis Figure 5G. Shape and Form of Cedars Figure 5F. Foliage Color and Texture of Conifers too deep, the root may suffer from lack of air and vines in decorative containers or planters. Proper selection of plant material and container is important to ensure a functional and healthy container garden. A fast draining, porous media is important to provide air space; but a media needs to have water-holding capabilities that will provide water to the plant. Clay, heavy soil or poorly drained soil can be a primary cause for plant failures in container gardening. A good container media would contain peat moss, organic materials, sand (for weight) and sandy loam soil. Peat moss provides good water-holding capabilities in the media but is difficult to rewet. When potting, be sure that the media level is about one inch below the edge of the container to make watering easier and more efficient. Also, do not place the plant too deep in the media. The top of the root system should be level with the media surface. If planted space. Watering thoroughly each time you water can prevent salt buildup from fertilizer release. However, be careful not to water too quickly because the water will leach out of the container and the media and the root system will become very dry. Sometimes the media can shrink away from the sides of the container. This may cause the irrigation water to run down the sides and out of the container without wetting the media. If this happens, soak the plant and container in a bucket of water until the media is resaturated. Mulch can help regulate the moisture in a container. Fertilizer application should be frequent for containerized plants. Routine watering may leach some of the fertilizer out of the container, so light and frequent fertilization is usually the best approach Container gardening has become a popular landscaping technique. Plants can be potted and protected in the early spring and late fall to extend the time that plants are contributing to the landscape. The flexibility and unlimited Tennessee Master Gardener Handbook 225

8 ideas of container size, dimension and choice of plant material can provide much enjoyment in the garden. Purchasing Plants Trees and shrubs can be purchased from the grower as seedlings or transplants. Seedlings are germinated from seed and grown for one or two years in the field. Bare-root seedlings have been dug directly from the field and are shipped without dirt or planting pots around their roots. If not planted immediately, seedlings must be heeled in, temporarily planted in a holding bed to prevent drying out. Seedling trees are the most economical for planting because growers can raise more trees per acre and can minimize the cost of materials and handling. Seedlings dug and placed into nursery beds or pots and grown for another year or two are known as transplants. Transplants cost more, but are generally stronger, sturdier and have better root development. Nursery stock with sturdy, compact root balls can better withstand planting stress. While growing in the nursery, container stock can be moved apart as they grow to allow better and more even development of each young tree s shoot system. When purchasing plants, there are two important points to take into consideration. One is to purchase plants from a reliable nursery or garden center. The second is to choose plants that will grow in a selected area of a garden. Many times, plants are purchased because of certain aesthetic characteristics with no regard When purchasing a plant, it is also important to inspect the leaves, branches, stems and roots to ensure that the plants are healthy and have vigorous growth. Leaves should be checked for signs of leaf spots, wilt and good coloration. Yellow color brown edges may to the cultural requirements. indicate a root problem. Also, plants that are wilted or have discolored foliage may be diseased and could introduce a new pathogen into the garden. Branches should also be checked for new shoot growth. The branches should be even or balanced on all sides of the plant. In addition, upright trees should have a straight trunk with a central leader. If the leader is dead, it is hard to prune and encourage a new leader. If deciduous plants are being purchased in the dormant season, the plant needs to be checked to ensure that it is alive. This is done by gently scraping the bark with a thumbnail or knife. Green tissue or moisture should be visible. If the exposed area is dark brown or gray and there is no moisture, then the branch or the entire plant could be dead. Thus, this type of plant as well as any plant with scarred or scuffed trunks and branches should not be purchased. Establishment Providing a plant with a proper start is vital to its success in the landscape. For optimal success, woody plants should be planted during a certain time of year and at a certain size or stage, depending on the species. Proper planting is also important to establishment. It is imperative that Master Gardeners be able to understand and explain how to properly prepare and dig a hole for the size of plant being planted. Timing Although spring is a popular planting season, fall is the best time to plant woody ornamentals. In the fall, plant shoots need fewer nutrients because winter dormancy is approaching. In addition, carbohydrates produced in the leaves move to the roots, which help with plant growth and survival. Importantly, roots continue to grow until soil temperatures drop below degrees F. Therefore, always water when planting in the fall, as October and November are usually very dry months with little rainfall. Fall-planted plants will not need as much summer irrigation as ornamental plants planted in the spring. A large number of plants are killed between leaving the nursery and being planted in the landscape because of mishandling. Fortunately, many of these deaths can be avoided by following a few simple steps. Start by avoiding windburn and plant desiccation by covering plants with a tarp during transport. Other best management practices for transporting, handling and planting these plants will help reduce homeowner and contractor losses. Keep in mind that recommendations change with time. Tennessee Master Gardener Handbook 226

9 Plant Size The size of a transplanted tree has a significant impact on the success and rate of establishment of a tree. Large trees require more time than smaller trees to adapt to a new site and to establish a comparable root system. Research has demonstrated that compared to large trees, small transplanted trees establish quicker and result in larger, healthier trees. This is partially because smaller trees are able to grow by adapting to site conditions. This allows them to better recover from stress. Depending on the species, trees that have a trunk diameter the size of an average person s thumb are considered small enough to adapt well. Planting Preparation for planting is the key to the success of landscape plants. Preparation includes site analysis, design, plant selection and installation. It also includes follow-up care and maintenance. Proper planting assures rapid plant establishment and healthy growth, provided environmental factors are favorable. However, proper planting involves much more than just digging a hole and sticking a plant in it. By taking a little extra time to plant properly, future costly maintenance problems can be avoided. The optimal months to plant ball and burlap, bare-root and containerized plants are listed in Table 6 (at end of chapter). Soil Compaction and Drainage construction of new homes and leaving only the subsoil. Also, during construction, heavy equipment compacts the soil, thus reducing air space. What little air space is left fills with water after a rain. This causes the roots to die from lack of air and the shoots to die from lack Many landscape plants die because they are planted in soil that is either too wet or too dry. Wet soils occur when the soils have poor drainage. Poor drainage can happen as a result of contractors removing the topsoil during of water, since the roots are no longer functional. Dry soils often occur during drought when rainfall is scarce and supplemental irrigation is not provided. In addition to changes in soils because of construction, the drainage pattern of native soils may alter over a long period of time. A hard pan may occur in areas that have had a lot of traffic or areas with repeated use. A hard pan is a layer of soil, about 12 to 15 inches deep, that is extremely compacted and can obstruct good soil drainage. Deep tilling is recommended to break up this compacted layer of soil. In areas where it would be difficult to use equipment, a dry well can be dug to break through the hard pan. After the planting hole is dug, a posthole digger can be used to dig a hole that is about 12 to 15 inches deep. This hole, which is the dry well, should then be filled with porous material such as gravel before planting the ornamental. For more information on soil compaction and drainage, see Chapter 3, Soils. Bed Preparation and Soil Improvement When installing groups of trees, shrubs or flowers in a large space, it is best to first collect soil for a soil test to see what nutrients and amendments are needed. See Chapter 3, Soils and contact your local county extension agent for more information about submitting soil samples. After receiving the soil test results, till soil 8-10 inches deep and add 2 to 3 inches of organic material or topsoil, as well as any lime or other nutrients as directed by the soil test results, spread evenly across the top of the tilled soil, then till again. One cubic yard of organic material applied 3 inches deep will cover 100 square feet of the planting bed. Rake the soil surface smooth to help make sure that some plants do not sink into low spots where water will accumulate. The bed is now ready to plant. Call Before You Dig! STOP! Call before you dig! Before digging anywhere, always contact your local utility offices. In most areas, utilities will locate and mark underground pipes and cables at no charge Tennessee One Call System Tennessee Master Gardener Handbook 227

10 Figure 6. Planting Depth after planting, the exposed part of the root ball should be covered with mulch. In a really moist soil, plants can be set on the ground and then a well-drained soil or fine mulch can be mounded around the roots. In dry weather, these plants will need to be watched closely to see if they need water. Planting Container Grown Woody Ornamentals Figure 7. Balled and Burlap Trees Growing in a Nursery Preparing the Hole When planting individual plants, it is important to dig the hole two to three times wider than the root ball. A wide hole provides room for roots to grow to the sides and away from the plant. Slope the sides of the hole too; this will allow new feeder roots the most room to used to roughen the sides of the hole, especially in a high clay soil. Clay that is wet can glaze when dug as the shovel pan creates a slick, waterproof barrier. Roots also have difficulty penetrating the walls of a glazed hole. a well-drained soil, the hole should be grow. The edge of a shovel or spade should be dug as deep as the root ball and the root ball should sit on solid ground, rather than loose soil. Otherwise, the plant will settle and, as a result, be planted too deep. A shovel handle or stake can be laid across the hole to help show the correct depth of the root ball in relation to the ground soil line. In a poorly drained soil, the hole should be dug 1 to 2 inches shallower than the root ball. Doing this raises the roots high enough to let water drain away from the roots. Then, Container-grown nursery plants need special handling to ensure proper landscape growth and survival. Before planting, water container plants then remove the container or plastic bag from around the roots. If the container was a fiber pot and appears to have been treated with a preservative, then remove it before planting. Check for, and do not be afraid to cut, any circling or girdling roots. Use a sharp knife, to make three or four vertical, ¼-inch deep cuts down the root system. This type of root pruning cuts circling roots and stimulates new root growth. Gently loosen the cut root ball to expose other roots to the surrounding soil. Next, place the plant in the hole so the top of the container soil is even or 1 to 2 inches above the soil grade and then backfill half of the hole with soil. Finally, finish filling the hole with existing soil, water again and rake soil so the backfill is even with the existing ground line. The top of the soilless container media will still be visible, so cover the entire area and container root ball with 2 to 3 inches of mulch. For more information on container grown plants and how to plant them, see Chapter 10, Herbaceous Landscape Plants. Planting Ball and Burlap Woody Ornamentals Ball and burlap (B and B) plants are field grown in nurseries. Typically, these plants are dug during the dormant season and sold during the fall through spring. In the past few years, mechanized equipment has been designed for B and B production, enabling some nurseries to dig plants during the spring and summer. These plants need to be acclimated before transplanting in the landscape. The root system on B and B plants is more difficult to check than containerized plants. To check the root system of B and B plants, feel the ball to be sure it is firm and not broken Tennessee Master Gardener Handbook 228

11 Considering Soil Amendments The addition of organic amendments should be addressed on a case-by-case basis. Organic amendments, such as peat moss, rotted animal waste or composted yard waste, are applied to soils to improve their nutrient-and waterholding capacity. In general terms improve the tilth of the soils. Rarely is it recommended to add organic amendments to an individual planting hole. Extensive research at Southeastern universities has determined that organic amendments placed in the planting hole do not result in a larger root system or encourage root penetration into the native soil. When a planting hole is amended, the structure and texture of the soil in the hole differ from that of the surrounding native soil. This encourages the roots to stay within the confines of the hole and discourages them from growing into the surrounding soil. The water movement between the surrounding native soil and the soil in the hole is disrupted and the planting hole can act like a sponge, holding excess moisture after rain or irrigation. It is best to incorporate organic matter uniformly throughout the projected root zone as opposed to putting it into the planting hole. To have an affect of the water- and nutrient-holding capacity of a soil, at least a one percent increase in organic matter is required. To achieve a one percent increase in organic matter, apply 500 pounds of an organic amendment per 1,000 square feet of bed area (50 pounds per 100 square feet) and incorporate to a 6-inch depth. A 25 percent increase in organic matter would be achieved by adding 3 inches of composted material to the soil surface and incorporating them to a 12-inch depth. Avoid using more than 50 percent organic matter because plant problems may result from humic acids and other organic compounds. Apply the amendment uniformly over the existing soil that has been deep tilled (8 to 12 inches). Till or work the amendment in the soil until a homogenous mixture is developed. inside. If the bag is broken, the roots have been damaged. Check for weeds in the rootball. Weeds growing out of the burlap may mean the plant was dug weeks or months ago. It is also difficult to tell if the roots have been kept moist or to inspect for winter damage. Typically the damage will not be apparent until Figure 8. Planting Balled and Burlap Plants the weather warms up and the plant begins to show signs of stress. To determine health of the plant, it is also important to move the main truck to and fro. The entire plant and rootball should move. If the trunk moves and the rootball does not, then roots could be broken and the plant may not survive transplanting. Looking at the leaves, branches and roots can also be useful in selecting a healthy plant. Avoid purchasing plants that do not appear healthy, even if they are bargains. When handling B and B plants, lift the plant from the rootball and not the trunk. Large plants may require two or more people to carry them, or the use of a tree dolly to transport them to the site. If not planted im- mediately, place the plants in the shade and keep the ball moist. The rootball can be covered with moist sawdust or bark until planting time. Measure the depth and width of the rootball to make sure the planting hole is the same depth, or a couple of inches shallower to allow for settling, and about two to three times wider. Place the rootball in the hole. Untie any rope, jute or nylon that is tied on Tennessee Master Gardener Handbook 229

12 Figure 9. Planting a Bare-Root Plant the trunk of the plant. Pinning nails should also be removed from the top of the rootball. Fold the burlap down, about one-third, around the rootball. Cover the folded burlap with the backfill or cut off the top third of the burlap. It is not necessary to remove the wire basket from large trees and shrubs. Cut off only the top ring of the wire basket. The lower portion of the wire basket will help support the rootball until new roots start growing. Backfill half of the hole with existing soil. It is not necessary to amend the backfill with organic matter because additional organic matter in an individual hole may cause a problem with internal drainage of the planting hole and surrounding area. Water the root zone thor- oughly. Watering at this point helps the soil settle and removes air pockets. Finish backfilling and water again. Rake the soil evenly over the entire area so the backfill is even with the existing soil line. Cover the entire area with 2 to 3 inches of mulch to help hold water and keep weeds from germinating. Planting Bare-Root Woody Ornamentals Bare-rooted plants have soil washed or shaken from their roots after digging. Many deciduous trees and shrubs, including fruit trees and nut trees, are sold this way to decrease the cost of shipping. These plants are dug in the nursery during the dormant season and are best purchased while still dormant. Many wholesale nurseries and mail-order nurseries produce bare-rooted plants; wrap the roots in peat moss, sphagnum moss or excelsior; and package them in cardboard boxes or plastic bags. These are known as packaged plants. Bare-root plants are also sold as processed balls. The root system is packed with compressed peat moss, sawdust or other moist material and shaped into a ball similar to a ball and burlap plant. Some nurseries use a stretchknit liner to hold the ball shape. The root system is put in a plastic bag for marketing. Fine roots may develop in the moist packaging material. When bare-root plants are purchased, it is important to open the box or plastic bag and check the root packing material for moisture. The roots will dry out quickly, and may cause the plant to suffer or die. Roots should be flexible, have multiple branches of roots and be evenly formed. Sometimes easy-to-transplant plant species, like roses and grapes, are sold bare-root without soil around their roots. Some plants are sold with their roots in plastic bags surrounded by damp sawdust. Be sure to keep the root systems of bare-root plants moist if plants are not installed immediately. They are more perishable than B and B or container grown plants. When planting these bare root specimens, remove any packaging material from the roots. Soak roots in water for up to 24 hours before planting. Remove broken and diseased roots as well as roots encircling the trunk. The hole for bare-root plants should be large enough to let roots spread out normally, without being twisted or cramped. In the bottom of the hole, use the native soil to mound a cone, hold the plant in place at the proper depth, and then spread the root system over the cone. The mounded cone will help support the roots when the backfill soil is replaced. As the soil is added, gently pack the soil around the roots to eliminate air pockets. When the hole is about two-thirds full, fill the hole with water and let it soak in. Finally, backfill, re-water and rake the soil evenly with the ground line and cover the entire area with 2 to 3 inches of mulch. Mulching at Planting Mulching is a very importantpart of planting. Mulching helps suppress weeds, moderates soil temperature from extreme fluctuations, maintains uniform soil moisture, defines the planting area and adds aesthetic value. There are many different mulching materials on the market, see Table 6. Common inorganic mulches are rocks, pea gravel, lava and woven (geotextile) materials. White rock and pea gravel are difficult to use effectively in a design, but they can be very attractive in Tennessee Master Gardener Handbook 230

13 Figure 10. Steps in Transplanting a Woody Ornamental the proper spot. These materials are difficult to keep clean and should not be used where they will get a considerable amount of leaf litter. Organic mulches are the most popular and probably less expensive than inorganic mulches. Materials such as pine straw, pine bark, shredded hardwood bark and composted leaves make good mulches. However, some mulches, such as grass clippings, often carry excessive weed seeds. Peat moss is an excellent mulch material, but the expense is usually prohibitive. Composted leaves are also good mulch material, but they should be shredded prior to use. If left whole, they tend to flatten into an impenetrable layer with a similar effect as plastic. Wood chips and sawdust may be used as mulch, but additional nitrogen is needed to compensate for microbial use of nitrogen. Mulch should be applied about 2- to 3- inches deep. More than 3 inches of mulch could be detrimental to plant growth. Keep organic mulch away from the base of the plants to prevent disease and rodent problems. Keep bark abrasion. Black plastic is a material commonly used by home gardeners and landscape professionals. However, care should be taken not to use plastic in areas designated for planting. This is because plastic does not allow for water and inorganic mulch away from the base to prevent air movement in and out of the soil and can eventually cause plant mortality. Weed mats or landscape fabrics can be used under mulch to provide good annual weed control. Weed mats are porous and allow water to penetrate to the root zone. However, these materials are unattractive and should therefore be used in conjunction with aesthetic mulch. Mulch containing cellulose, such as pine straw, bark, wood chips and leaves should not be placed up against the foundation of a house or other structure. This is because cellulose containing mulches can give termites access to the structure without contacting a termiticide. Pruning at Time of Planting It is not necessary to prune woody ornamentals at transplanting. In fact, research shows that plants pruned at planting grow no better than un-pruned plants, and in some instances pruned plants grew less than un-pruned plants. In part, this is because pruning removes vital plant tissues that produce plant hormones like auxins. Auxins are stored primarily in the shoot tips and stimulate both spring bud break and root growth. Therefore, removing shoot tips can promote tall, leggy plants with bushy bases and delay bud break in spring. Transplanting Established Woody Ornamentals Before transplanting a plant in the landscape, prepare the plant for the move. At least six months to a year before moving the plant, determine the proper size of the root ball to be dug. The American Nursery and Landscape Association (ANLA) recommends a inch root ball for every inch of plant caliper diameter measured on the main stem. Therefore, if a plant has a 2-inch diameter caliper, the root ball should be inches in diameter. Steps in Transplanting a Woody Ornamental (Figure 10): 1. Draw a circle on the ground around the trunk, then draw a second circle about 2 to 3 inches inside the first. 2. Use a sharp spade and cut the blade into the soil about 8-12 inches deep in the north and south quarters around the inner circle. 3. Three to six months later, repeat the process on the east and west quarters of the inner circle. This will help save the many new feeder roots that develop from the severed roots by keeping them within the outer circle (dug) area. 4. After another three to six months (after cutting the root system) and during the dormant season, the plant is ready for transplanting. If soil moisture is low, Tennessee Master Gardener Handbook 231

14 water the plant a couple of days before transplanting. It is also important to tie branches out of the way with twine. 5. Next, dig a shallow trench around the outside of the original root ball circle, and then dig completely around the root ball while keeping the root ball intact. 6. Gently roll the ball to one side and place a large piece of burlap around the root ball. Roll the root ball to the other side so the burlap covers the entire root ball. 7. Firmly wrap the burlap and tie it around the root ball for the move. A root ball inches wide may weigh several hundred pounds, so do not lift the plant by the trunk or stems. For easier handling and to reduce lifting, carefully roll the root ball onto a tarp and drag the plant to the new planting site. 8. Plant the tree or shrub according to the best management planting practices described earlier. Transporting Plant Material When transporting plants, always handle ball and burlap and container plants from the rootball or the container. It is important to never grab plants by the foliage or the trunk without supporting the rootball. This is because roots can be broken when the soil mass pulls downward while the plant is lifted by the trunk. In addition, be sure to protect the plants while transporting them home. High winds can cause excessive water loss, turn leaves Figure 11. Truck Girding on a Japanese Cherry The amount of water needed is dependent on brown and possibly kill the plants. Therefore, lay plants down in the bed of a truck with the top of the plant toward the rear. Use a tarp to cover the foliage of trees and large plants to prevent damage. When arriving home or at the landscape location, set the plants in a shaded area and avoid setting them on asphalt or concrete, these surfaces radiate large amounts of heat. Large ball and burlap trees should be laid on their side. Water plants thoroughly and continue watering on a regular basis until plants are installed. Care and Maintenance Good post-transplant care is important for the plant to have healthy growth. Containergrown plants may be susceptible to drought stress once they are transplanted to the landscape. Drought stress occurs because the welldrained container media in which the plants are grown in the nursery is prone to rapid moisture loss. Even through soil moisture is available in the soil surrounding the container media, it does not move into the container media fast enough to alleviate moisture stress. For this reason, these plants should be observed closely after transplanting in the landscape and watered thoroughly when needed. Many newly planted trees and shrubs show little shoot growth during the first year or two. But they are developing root systems. Proper methods of handling plant materials and providing good soil preparation, nutrition and water will help trees and shrubs establish in the landscape and will reduce losses experienced by homeowners and contractors. Watering Watering newly set plants is essential for early growth and survival in the landscape. A strong root system will produce a better plant, which is able to withstand dry periods later. soil type, rainfall and plant species. If the soil moisture level is high, then oxygen levels may be low and adding more water can suffocate the plant. A good rule is to water at about fiveto seven-day intervals with enough water to soak the root ball. Tennessee Master Gardener Handbook 232

15 Staking and Stabilization Most plants do not need to be staked and guyed after transplanting. However, trees with large canopies, large evergreen shrubs or trees planted in windy sites should be staked and guyed for stability during the first year after transplanting. A general rule of thumb is to stake and guy plants with a caliper greater than 2 inches or taller than 8 feet. Staked plants should have some flexibility rather than being held rigidly in place. For more information on staking and stabilizing plants, see the training sections in Chapter 12, Fruit and Nuts. Staking Staking is a controversial subject. There is much disagreement about whether it should be done, and if it should be done, how should it be done and with what materials. The goal of staking is to hold the root ball still while allowing the trunk to sway a little, thus promoting good taper toward the base. The staking guidelines below have been adapted from Dr. Bonnie Appleton at Virginia Polytechnic Institute and State University. inserted at least 18 to 24 inches into Wooden and fiberglass stakes or posts are good for short-term tree stabilization. For trees less than 2-inch caliper or 6-8 feet tall, use a single stake the native soil. Trees with up to a 6-inch caliper need two stakes; larger trees need three or more stakes. Root anchor products are often preferable to support lines, particularly in areas with foot and animal traffic. Keep in mind that root anchors left in place may present future problems for tree removal equipment. guys, which can damage thin bark. If support lines are needed, use either plastic (poly) chain lock or woven cloth (web) strapping instead of wire and twine If the tree is in traffic areas, tie flags or ribbons on guy wires to protect pedestrians and pets. Loosely connect supports or guides around the trunk to allow slight movement and trunk caliper and taper growth. Do not anchor trees too high on the trunk and avoid securing guides in narrow crotch angles of branches. Prevent bark abrasion, particularly on thin-barked trees like maple and cherry trees, by using recommended rubber bands, pads or springs with supports or stakes. Cut pieces of hose degrade very quickly if used with thin wire or left untended. Padded supports should be just tight enough to prevent the tree from tipping and low enough to permit some swaying motion. Remove stabilizers after new root growth adequately penetrates existing soil. This usually occurs after the first year. However, keep in mind that slow growing trees may need a little bit longer to be self-stabilizing. Trunk Wrapping As mentioned above, most tree trunks are wrapped at the nursery to prevent bark injury during shipment. These wraps can be made of burlap, paper sacks or any other material that can provide some protection. There are also some commercially available wraps, such as craft paper, burlap fabric and rigid pvc that can be used on newly planted, thin-barked trees to protect them in hot, sunny locations. However, research indicates that tree wraps do little to protect transplanted trees against sunscald or frost cracks, unless trees are planted in areas of high-reflected light or heat, such as parking lot islands. If these products are used, they should not be attached with wire, rope or heavy tape because girdling can occur. Additionally, wraps should be removed after one year to prevent insect and disease problems as well as water damage to the trunks. Fertilizing Woody Ornamentals A soil test will determine the acidity or alkalinity (ph) of the soil, as well as essential nutrients. Most ornamental plants grow best when the ph range is between 5.5 and 7.0. The local University of Tennessee Agricultural Extension office can provide instructions for taking a soil sample. Detailed instructions on taking and submitting a soil sample can be found in Chapter 3, Soils and Plant Nutrition. Tennessee Master Gardener Handbook 233

16 Tree Inspections Fertilization of Newly Planted Ornamentals Most Master Gardeners will normally look at a tree because someone asked them. The request could be from a homeowner, a business owner or a municipal official. The reasons for the request can be as varied as the people who make them. However, knowing why people want advice will determine how to approach each inspection. People request tree inspections because: A storm or other catastrophic event occurred It is part of a periodic routine A tree looks unusual They need help selecting a treatment or action for the tree s health or safety They want peace of mind about a tree s safety They need help resolving a personal conflict or dispute (sometimes unrelated to the tree) between two or more people Regardless of the reason for a tree inspection, it is important to be flexible. For each tree request, there is a person who has a stake or interest in the results. Knowing this will help the Master Gardener focus his or her attention and efforts in a way that will result in a meaningful outcome. Additionally, it is a good idea to always seek advice from professionals to confirm your findings. For a Master Gardener Tree Inspection sheet, see the appendix. Also, for more information on plant inspections, see Chapter 20, Diagnosing Plant Problems. Soil tests should be done either during the development of a new area or landscape bed, or a couple of months prior to fertilizer ap- between the time of soil testing until the time of fertilizer application. For instance, if a fertilizer application will be made in early spring, then soil should be tested in the fall to allow for the turnaround time of the lab. It is important that plants not be over plication. There should be four to six months fertilized and that fertilizers not be expected to overcome problems caused by improper planting techniques, poor soil drainage, soil compaction or incorrect watering practices. The best action is to determine the specific cause of poor growth and apply corrective measures. Do not assume that an application of fertilizer will quickly remedy any problem that is encountered. For additional information on soil nutrition, see Chapter 3, Soils and Plant Nutrition. There is an ongoing debate about fertilizing newly planted trees and shrubs. Most of the growth a plant puts on in its first year is spurred by carbohydrates and minerals already stored in the plant. This underscores the importance of buying a healthy plant from a reputable nursery. However, applying fertilizer at planting will help ensure that the plant stores sufficient nutrients for the following year. If granular fertilizers are applied at planting, the fertilizers should not come in contact with the roots of the plants. Therefore, fertilizers should be broadcast over the soil surface. Because formulations and release patterns vary from one fertilizer to another, it is best to follow the manufacturer s recommendations on application rates. Liquid fertilizers used as a drench at planting will readily leach and will not provide a long-term benefit. Fertilization of Established Plants In many yards, a good lawn maintenance program may eliminate the need for supplemental fertilization for trees and other woody plants in the lawn. General tree vigor is determined by comparing the length of twig growth during the past three or four years. Young trees should have at least 9 to 12 inches of terminal growth per year. Large mature trees usually average 6 to 9 inches of growth. Shrub vigor is determined the same way as young trees. Plant signs indicating the need for fertilization include lack of terminal growth, pale green or yellow leaves, mottled leaves, dead branches, stunted leaves, and early leaf drop in the fall. If a granular fertilizer is used, the ideal months to fertilize are March through June. However, some plants, such as roses and annuals, are considered heavy feeders and benefit from light, frequent fertilization on a monthly basis during the growing season. Other factors to consider when fertilizing plants include desired growth rate, type of plant, soil type and type of fertilizer. Tennessee Master Gardener Handbook 234

17 Applying Fertilizers The best time to apply a fertilizer is in the spring before plant growth begins. Root growth starts as the soil temperature rises, prior to shoot growth. The maximum growth response to the fertilizer is obtained when fertilizer is available in the root zone while the roots are flushing. Fertilizers should not be applied from Aug. 1 through early winter. Late summer fertilizing can stimulate an excessive amount of new growth, making plants more susceptible to winter injury. Another reason not to fertilize during this period is that the plant will not take up a lot of nutrients. This will cause nitrogen and phosphorus to leach from some soils and create an environmental concern. Plant growth is limited by nitrogen deficiency more often than by phosphorus or potassium deficiency. For this reason, a fertilizer with a or ratio can be used for trees. If the desired ratio is unavailable, a complete balanced fertilizer such as or can also be used. The same types of fertilizer can be used on shrubs and vines. Slow-release or controlled-release fertilizer generally cost more than general purpose fertilizers, but their release duration compensates for their higher initial cost. When fertilizing around trees and shrubs, be sure to treat the entire area below the branches of trees and shrubs. On large shade trees about one-third of the fertilizer should be applied beyond the drip line. Additionally, to obtain even distribution, divide the fertilizer in two equal lots and apply one-half lengthwise the area. After fertilizing, water the area thor- over the area and the remainder crosswise over oughly, soaking the soil to a depth of about 6 inches. About 80 to 90 percent of the fibrous roots of plants are in the top 12 inches of the soil. For more information on irrigation, see Chapter 4, Water Management. Pruning Pruning is one of the most important cultural practices in the landscape. In fact, correct pruning may add years to the usefulness of the plant. Rarely will one find a tree, shrub or vine that does not need some pruning each year. Proper pruning will help produce a more attractive, vigorous and well-formed plant. In many cases, flowering will also increase. One should never hesitate to cut tall, fast-growing or unsightly limbs. Too many homeowners neglect their plants and fail to prune for several years. Shrubs in particular become overgrown and lose vigor. When this occurs, heavy pruning or severe renewal pruning is needed to reduce plant size. Remember, if the terminal bud on a new shoot is lightly pruned, lateral growth will produce a fuller plant. Pruning should begin when plants are young. Early pruning on shrubs will increase the branching structure near the ground and develop a more compact plant. Pruning young trees correctly will ensure a straight center leader and scaffold branching. Trees need to be pruned correctly as they grow to eliminate massive corrective pruning when they are mature. Why Prune The primary consideration in pruning must be safety. Many people are apprehensive about pruning, but knowing how, when and why to prune will end these fears. Pruning cuts should be made for a reason: To remove potential hazards in large trees: dead wood or branches that are in danger of breaking or falling during a storm To maintain plant health To remove misshapen, crowded and rubbing branches and branches with narrow crotch angles; these pruning cuts eliminate problems before plant damage occurs To increase flowering and fruiting To train plants to a particular size or shape, including hedge and espalier forms To rejuvenate old, overgrown shrubs and restore plant density, shape and vigor. To increase visibility Tennessee Master Gardener Handbook 235

18 Remove Potential Safety Hazards Large trees in areas where people can be harmed can be considered hazardous if the health of the tree is in jeopardy. To keep a tree from becoming a potential hazard, monitor the tree and remove potential problems from incorrect growth or damage as they develop. When hazards from large limbs or branches are spotted, especially those near power lines or other areas that may be high liability (parks and playgrounds, parking lots, homes etc.), make recommendations to contact the municipal agency or utility responsible. Volunteers can learn to recognize these hazards: Trees in contact with or near power lines! DO NOT ATTEMPT ANY PRUNING OF SUCH TREES! Weak tree structures, especially trunks or branches with included bark or co-dominant leaders, these are likely to fall in high winds Hangers branches that have partially broken free but have not fallen Cracks or splits in the trunk, branches or branch attachments Lodged trees, which are supported by other trees nearby ground, or whose top is not growing straight upward Trees with root damage from construction, trenching, grade Leaner trees, which have roots that are tearing from the change (cut or fill), mower injury, pavement repair, etc. Trees with severe pruning or topping Trees with dieback of leaves, twigs and branches Trees with signs of decay: rotten places or cavities in trunk or branch wood, mushrooms or conks on the trunk or branches, or soil over the root system cuts or ruin pruning tools. Figure 15. Common Tools for Pruning Woody Ornamentals Solutions to hazardous tree situations include: Move potential targets, objects that might be damaged or attract people to spend time under a defective tree Maintain the tree s health: properly prune, water and fertilize Professionally cable or brace the tree Consider removing the tree Consult a professional for assistance with large-scale work Keep in mind that even proper pruning leaves physical wounds on plants and can have several important plant health outcomes. Deciduous shrubs produce new growth from terminal buds. These terminal buds produce the growth hormone auxin that controls Pruning for the First Time When pruning a tree or shrub for the first time, follow these simple steps: 1. Remove all broken, dead and diseased limbs. 2. Remove crossover branches or branches that rub together. 3. Cuts should be made just outside the swollen branch collar, which is where wound healing begins. 4. Take care not to damage the bark around the pruning cut. Do not wiggle pruning tools to cut into a branch too large for the tools. Wrong sized or incorrect tools will either leave jagged 5. Never leave a stub. Stubs produce weak stem suckers and provide a place for pests and diseases to attack. 6. Do not paint or tar pruning cuts. This ineffective practice does not provide any plant health benefit, interferes with the plant s own wound defense system and does not deter insects or diseases. Tennessee Master Gardener Handbook 236

19 Figure 16. Apical Dominanace is Influenced by Auxin development and growth of side buds lower on the branch. This growth control is called apical dominance and is strongest in upright-growing shoots. Thus, if the terminal bud is removed, lateral buds at nodes along the stem are stimu- lated to grow because the auxin is missing. In fact, on plants like crabapple and magnolias, apical dominance is totally lost on horizontal branches. This causes lateral buds on upper sides of branches to develop vigorous, upright water sprouts that limit the plant s natural growth habit. Tools of the Pruning Trade Only a few key tools are needed to prune correctly. Invest in high quality tools and keep them sharp. Sharp blades leave smooth cuts that heal faster and help reduce disease problems. Tools needed for pruning are listed below. 1. Hand clippers: Hand clippers are used for removing branches less than ½-inch diameter. Anvil clippers are used on dry, old growth with less than ¼-inch diameter and on plants that do not have hollow stems. Two-bladed bypass clippers give the cleanest cut on new green growth and on roses or other shrubs that have hollow, thick stems. 2. Loppers: Loppers are 20- to 36-inch long tools for pruning ½- to 1½- inch diameter limbs. Loppers have distinct curved shear and cutting blades. 3. Hedge shears: Head shears are used for developing a formal, shaved or sheared appearance. Hedge shears are the pruning tool most often used incorrectly and produce indiscriminate heading cuts (see Figure 15). Do not use hedge shears on any shrub where a natural shape is desired. 4. Pruning saws: Use pruning saws to remove 1 ½-inch and larger diameter limbs. Do not use a carpentry saw. Invest in an arborist s saw that has a narrow, 12 to 15 inches, long and curved blade. Some of the most effective pruning saws have saw teeth angled toward the handle that cut on the pulling stroke. Other saw blades have teeth designed to cut on both push and pull strokes. 5. A combination pole saw with pruners: This tool provides a 10- to 12- foot long handle for cutting difficultto-reach branches. Pole saws and pole pruners may be purchased as separate tools or as a combination tool. Purchase a fiberglass pole handle and use extreme caution when pruning near electric lines to reduce risk of electrocution. 6. Electric, gas and battery powered pruners: These tools are also available, lightweight and powerful. Gas powered fixed- or variable-length pole pruners have a light, two-cycle engine connected to attachments that can include a small chainsaw blade, string trimmers or bypass clippers. Tennessee Master Gardener Handbook 237

20 Figure 17. Important Pruning Parts of a Tree A. Branch Leader B. Primary/main scaffold branch C. Secondary/main scaffold branch D. Lateral Branch E. Water Sprouts F. Strength in Angles G. Suckers Figure 18. Water Sprouts When to Prune It is just as important to know when to prune, as it is to know how to prune. Pruning can be done almost any time of the year, but there are optimal times for plant response. A plant s energy reserves are highest during the dormant period of winter and lowest during spring growth. Therefore, the best time to prune is in late winter and early spring. Plants have plenty of stored energy, are ready to grow and the possibility of freeze damage is low. Dormant pruning may reduce the amount of flowers on spring-flowering shrubs, but it may be needed to maintain the desired growth habit. The next best time to prune is early summer, after the foliage has matured. When powdery mildew or fire blight diseases are active, plants should be pruned when the foliage is dry. The goals of early summer pruning should be height reductions and increasing shrub density. If plants are pruned during active spring growth, plants must shift already low energy reserves into growing new shoots and healing pruning wounds. Late summer and early fall are also bad times to prune because new growth, which cannot mature enough to withstand winter freezes or early fall frost, spring, the flow of sap will stain tree bark and Tree Topping is encouraged. An old rule is: Do not prune when the temperature is below 20 degrees F. Pruning in late fall or early winter will keep wounds open until spring, inviting desiccation. That being stated, birch, elm, maple and yellowwood trees are known as bleeders, and should be pruned in late winter. If pruned in attract pest insects. When seasonal plant flowering and appearance are of critical importance, consider plant flowering and fruiting habits. As a general rule, plants that flower before July 1 should be A practice called topping is a severe threat to tree health and is a common problem in Tennessee. Topping is particularly visible where it has been used to reduce tree height around homes and utility lines. There is never a good reason to top a tree. Topping removes the tree s main leader and branches, resulting in stubs and large wounds that never heal properly and greatly shorten the lives of trees. After topping, new growth is disfigured by water sprouts and weak limbs that produce a dense canopy with poor air circulation. Insects and disease organisms thrive in this environment. For these reasons, the International Society of Arboriculture s Arborist Certification Program does not endorse topping. Instead, certified arborists practice crown reduction and drop-crotch pruning under narrowly defined conditions. Tennessee Master Gardener Handbook 238

21 Figure 19. Tree Topping of a Star Magnolia Figure 20. Renewal Pruning Severe Renewal Pruning pruned immediately following flowering, see Tables 7 and 8 below. Such plants include azaleas, forsythias, plums, cherries, weigela, mock orange and oak leaf hydrangea. These plants develop flower buds on the previous season s wood. Therefore, pruning in July promotes shoot growth and allows time for new flower buds to develop for the next year. If pruning is delayed, any pruning will remove potential flowers for the next season. Plants that flower after July 1 should be pruned before growth starts in late winter or early spring, see Tables 8 and 9. Summer-flowering plants like crape myrtle, rose-of-sharon, vitex, butterfly bush and some hydrangeas develop flower buds in early spring on the current season s growth. Because they have produced flower buds on old wood, spring-flowering plants can be pruned immediately after flowering to avoid reducing floral display and to promote new growth. On plants where the fruit is as important as the flowers, delay pruning until after fruits have lost their aesthetic appeal. If pruning to control size and shape, dormant pruning is recommended. Plants prized for their fruit display, such as Pyracantha, holly, barberry, cotoneaster and nandina, should not be pruned until fruit has lost its beauty, regardless of plant flowering time. As needed, lightly thin branches on the plant during the dormant season. See Tables at end of chapter: Table 8. Spring-Flowering Shrubs Table 9 Spring-Flowering Trees Table 10. Summer-Flowering Trees and Shrubs Severe renewal pruning may be the only option for restoring a full vigorous growth habit to shrubs, including hollies that are overgrown or leggy. If severe renewal pruning is necessary, in late winter, all branches should be cut to within several inches of the ground. Latent buds that are already formed in the woody stems will break dormancy as weather warms. Because the plant already has an established root system, growth is generally stronger and faster than that of newly planted shrubs (Figure 20). Also, tip pruning new shoots will be needed to enhance lateral bud growth. Avoid using this technique on junipers and boxwood. Pruning Shrubs If major pruning cuts are made every three years, the plant selected for the site is probably wrong. A common example is where potentially large hollies, privet or photinia are planted in front of picture windows. It does not take long for these plants to grow to the point that the view from the window is obscured. There are many pruning styles for shrubs, but there are two basic pruning cuts: head- Tennessee Master Gardener Handbook 239

22 Figure 21. Proper Pruning Cuts A. Too far from bud B. too close to bud C. Too slanting D. Good Cut E. Good Cut on a conifer Figure 22. Thinning Cuts form. Enough of a stub should be left below the cut to keep the bud from drying out. Cut plants with opposite bud arrangement ¼ inch above the buds at a right angle to the stem. Usually, both buds will grow, produc- Thinning Cuts ing and thinning. Heading cuts often shorten a branch stem; thinning cuts remove a branch at its base where a side branch arises. Whether a shrub is sheared into a hedge or pruned with a natural growth habit, these two cuts are used. Heading cuts are made just above the nodes (Figure 23). The buds directly below a heading cut generally produce new shoots. To encourage shoots to grow outward and produce a spreading shrub, cut above an outward facing bud. Leaving the inward facing buds intact causes crowded branching and poor growth ing two equal new shoots going in opposite directions, which is often undesirable. Therefore, rub or cut off the unwanted bud. Maple, dogwoods and ash are common landscape trees that have opposite bud arrangement. It is difficult to maintain a center leader in these trees without diligent pruning. Thinning is a useful pruning technique for shrubs like Forsythia, Spiraea, Weigela, Mahonia, mock orange, Nandina and Eleagnus. These plants may be pruned by cutting about one-third of the older branches or canes back to ground level every few years. Resulting new growth increases plant density and flowering potential. About half the length of remaining leggy shoots should be removed to shape the plant. To maintain form and plant vigor, lightly prune new growth tips several times during the growing season. Tennessee Master Gardener Handbook 240

23 Figure 23. Hedging and Shearing Styles Needle-leaved evergreens that are flat on top and straight-sided or wider at the top than at the vvvbase shade lower branches and allow snow to accumulate on top of the hedge and damage the plant. Tops that are flat or somewhat wide are acceptable for areas with little snowfall, but not ideal. Rounded tops and wide bases shed snow naturally and allow light to reach the leaves. Deeply cutting back overgrown evergreen branches without sheering will give the plant a more natural appearance. Evergreens are pruned primarily to increase Shearing Hedges Formal hedges provide privacy and serve as an aesthetic backdrop for colorful plants, but they require regular maintenance to keep hedge size and shape optimal. Improper or unnatural pruning hides the plant s natural beauty and active pruning is needed to keep the geometric shapes. Needle-leaf evergreens, such as yew, arborvitae, hemlock and spruce, are adaptable to repeat shearing into hedges or sculpting into landscape plants. Keep in mind that shearing creates a major commitment to a rigid, timed pruning schedule. Shearing should begin with young plants, starting in mid- to late spring. A single early shearing produces a more naturalistic look because later growth hides the cuts. Regular shearing throughout the growing season can maintain more formal look. The sides of a properly sheared plant should be cut wider at the bottom than the top so lower branches are not shaded. When lower branches are shaded, too little food is generated by photosynthesis and non-productive leaves drop, creating a leggy plant. Also, avoid flat and wide hedge tops or snow and ice will accumulate and break branches. Instead, create a narrow or rounded top so ice and snow are shed naturally, Figure 23. Pruning Broadleaf and Narrow-Leaf Evergreens Conifers, broadleaf and narrow-leaf evergreens may be pruned any time that the wood is not frozen (Table 11). However, the optimal time to prune evergreen trees and shrubs is in the late winter or early spring, before new growth starts. Although to develop the desired size and shape, frequent pruning in the spring and summer may be necessary. foliage density and to reduce plant size. Cuttings taken in early December provide cuttings for holiday decorations. Conifers have whorls of lateral branches that develop from preformed latent buds in the shoot tip. Because conifers have very few latent buds in old wood, pruning back to old wood leaves no new buds to generate new foliage. Juniper and yew have numerous buds in the foliage, but they have almost none on older wood. Pine, spruce, fir, dawn redwood, Cryptomeria and cypress have few, if any, buds on old wood. Therefore, do not prune back to old wood when pruning these plants. To thicken new growth on pine and spruce trees, one-half the length of the new growth candle should be removed in the spring when it is about 2 inches long. Shears should not be used because they damage needles surrounding the candle and cut edges turn brown. Instead, the tender candle should be pinched with fingers or sharp hand clippers should be used. See Table 11. Evergreen Trees and Shrubs, at end of chapter. Tennessee Master Gardener Handbook 241

24 Figure 24. Pruned Conifer Tips Pruning Vines and Groundcovers The optimal time to prune groundcovers and vines is late winter or early spring, before new growth starts. Frequent pruning in the spring and summer may be necessary to develop desired size with vines. Vinca, ivy and wintercreeper groundcovers can be pruned with a lawn mower set to mow at the highest setting (Table 12). This pruning can be done once or twice during the growing season to control growth. Liriope can be cut in early spring to remove old foliage. The blade should be sharp and the cut made prior to new leaf emergence. Develop a strong, straight trunk, start early in the life of a young Figure 25. Training Young Trees tree and remove branches at positions 1, 2 and 3. The trunk should be limbed up only one-third to one-half of the height. For instance, if a tree is 6 feet tall, limbs that are about 2-3 feet above the soil line should be removed. If a more compact tree shape is desired, the C branches should be removed. If a more upright tree shape is desired, the A branches should be removed. If a more open tree shape is desired, the B branches should be removed. Keep in mind that more than one-third of the living branches should not be removed in any one pruning event. Also, all cuts should be made at the nodes or in the back to the next limb. The central leader should not be removed, cut or headed except to remove a tight group of terminal twigs so a more vigorous dominant shoot will develop. See Table 12. Groundcovers and Vines, at end of chapter. Pruning Young Trees Even though a large amount of tree roots are left in the production field when B and B or bare-root trees are harvested, it is not necessary, or desirable, to cut back the tree canopy -when transplanting. Research has shown that trees pruned at planting do no better, and sometimes do worse, than trees that are not pruned. If it tree is dormant, cutting it back can actually delay bud break in the spring and slow the tree s initial growth. For greatest strength, branches selected to become permanent scaffolds must have a wide angle of attachment to the trunk. Branch angles of less than 30 degrees from the main trunk have the highest probability of breakage (Figure 26), while those between 60 and 70 degrees have a smaller breakage rate. In part, this is because narrow crotch angles weaken when dead bark tissue is trapped in the space between two branches (Figure 26). Often, as limbs break due to bark inclusion, they tear bark down the trunk and damage supporting branches. In particular, Bradford pears have narrow crotch angles and are susceptible to limb breakage when they have been in the landscape for more than years. Tennessee Master Gardener Handbook 242

25 Figure 26. Narrow Branch or Crotch Angles & Bark Inclusion A. B. Narrow Branch or Crotch Angles Bark Inclusion On young trees, scaffold branches can be spaced about 6 to 12 inches apart. Young scaffold branches low on the trunk can be kept the first few years to help increase lower-trunk size and to protect the trunk from the sun. In time, however, closely spaced scaffolds will produce few lateral branches and result in long, thin branches with poor structural strength. There- fore, by about the fifth year, shade tree scaffold branches should be pruned from 8 inches to preferably 20 to 24 inches apart. There should be five to seven scaffold branches distributed to fill the radial space around a properly pruned trunk. Radial spacing prevents one limb from overshadowing another. Pruning Mature Trees Improper pruning can cause irreparable damage to mature trees. Most homeowners are only equipped to safely prune branches on large shade trees that can be reached from the ground. Removal of larger and higher limbs should involve the professional services of an arborist who has the proper skills, equipment and insurance. As stated above, never prune branches around power lines. Common methods of pruning large trees are crown thinning, crown cleaning, crown or height crown reduction and crown raising. The most desired method of pruning should be discussed with the arborist prior to the work being done. On mature trees, branches should be cut back to the trunk or to a lateral branch that is Arboriculture The International Society of Arboriculture (ISA) certifies that professional arborists have a minimum of three years experience and have passed a written exam regarding pruning, problem diagnosis, tree biology and safety. Certified arborists evaluate the location and condition of the tree and focus on maintaining tree structure, form, health and appearance. When hiring an arborist, check their references and make sure their liability insurance is current. at least one-third of the diameter of the parent branch, depending on the diameter of the limb. Each cut should leave a smooth surface with no jagged edges or torn bark. Heavy limbs and branches, with a diameter of 1½ inches or greater, should be removed using the three-cut method. Remember not to paint or tar pruning cuts. These ineffective practices interfere with the tree s normal wound healing process. Tennessee Master Gardener Handbook 243

26 Figure 27. Three-Cut Method for Larger Diameter Limbs 1. The first cut is a shallow saw cut about inches away from the trunk. This will prevent the branch from tearing bark from the trunk. 2. The second cut is a top cut about 3 4 inches past the undercut. 3. The third cut removes the stub just outside of the branch collar and should leave no tears or jagged edges. Both flush cutting into the branch collar and leaving stubs will lead to wood decay and slow healing of the pruning wound. Pruning Ornamental Plants to Control Insects and Diseases When pruning to remove an infection or insect infestation, sharp, sterilized pruning tools should be used to remove the entire affected area, cutting back at least 1 inch into healthy tissues. Pruning tools should be dipped into undiluted alcohol or a 10 percent solution of household bleach after each cut. Pruning should not be done when adult pests are present because other individuals may be attracted to the plant for egg-laying. Cut stems and diseased leaves should be raked up and removed from around the ornamental plant to avoid re-infestation. Wounding a Tree Carving into tree bark scars a tree forever because plant cells do not repair or replace themselves. However, trees can live after sustaining substantial damage to the interior wood or to areas of the bark, as long as the damage or disease does not spread to living cambium tissues. Structurally, however, these trees are weakened. Damage from scrapes or girdling wires cutting into the thin cambium layer beneath the bark may kill a tree, even Terms Associated with Pruning Large Shade Trees Crown cleaning: Selective removal of dead, dying, diseased or weak branches and water sprouts. though little damage appears on the surface. String trimmers, mowers, price tags and support wires cause much damage to trees in urban areas. Woody ornamentals wound defense is the unique ability for the woody growth to Crown thinning: Selective removal of healthy, live branches to increase light penetration and reduce weight. Cleaning typically done at the same time. One-half of foliage on the lower one-third of the tree must be left so thinned branches continue to grow and strengthen the limb. compartmentalize or wall off decay. Compartmentalization is the process by which trees limit the spread of discoloration and decay. Alex Shigo s proposed model of this process, CODIT (Compartmentalization Of Decay In Trees), identifies four barrier walls that a tree develops in response to an injury or wound. Alex Shigo was a plant pathologist with the United States Forest Service. Crown raising: Removal of lower branches for clearance of obstacles, traffic and pedestrians. Some arborists refer to crown raising as limbing-up the canopy. The first three walls form the reaction zone. Wall 1 impedes vertical spread by plugging inactive xylem vessels. Wall 2 slows inward spread by depositing chemicals in latewood cells. Wall 3 further halts lateral spread by activating ray cells to resist decay. To protect against the outward spread of decay, the next Crown reduction: Selective removal of both living and dead branches to reduce tree height or spread. Good crown reduction practices include cutting branches to larger laterals while not removing more than one-third of the tree crown in any single pruning event. layer of wood to form after injury becomes Wall 4 or the barrier zone. Tennessee Master Gardener Handbook 244

27 Figure 28. Compartmentalization in a Tree Wound or CODIT: Understanding compartmentalization makes it clear why most tree wounds require little assistance in closing. A raggedly broken branch should be pruned off. Be careful not to cut into the surrounding wood or to remove any healthy bark edges. Interfering with the cambium around the wound can slow or stop compartmentalization. Figure 29. Street Trees Survive Despite DIfficult Conditions The weakest of the barrier is Wall 1; the strongest is Wall 4. The new cambial ring forming around the injury creates an outer barrier. Interestingly, this explains why trees can continue to grow, forming healthy outer cambium layers despite a hollow, decayed interior. Wall 4 rarely fails, except in death of the new cambium, or if some canker-causing fungi restricts the development of the new growth ring. During every growth period, trees form new compartments over older ones. After injury, a boundary forms that resists spread of infection. This protects and preserves the water, air and mechanical support systems of the tree. It is important to realize that although no wound heals, including pruning cuts, they are walled off to protect healthy tissue. Hollow trees with large cavities lack stability in heavy winds and storms, and they may need to be supported or removed for safety. Trees and People Trees and greenery benefit a community in many ways: Trees beautify the landscape. Trees encourage community involvement and simply make life more pleasant by portraying that at-home feeling. Unfortunately, the average tree in a metropolitan area survives only about eight years! Trees provide wildlife habitat. Bringing natural elements and wildlife together into urban surroundings increases the quality of life for residents of a community. Trees reduce pollution, noise and dust. In one year, an acre of trees can absorb as much carbon as what is produced by a car driven up to 8,700 miles. Trees moderate climate, improve air quality and help conserve water. Trees provide shade and shelter, reducing yearly heating and cooling costs by $2.1 billion. Trees save energy costs by shading in the summer and by blocking winds in the winter. Trees release oxygen and water vapor into the air. Trees also reduce wind and water erosion. Trees increase property values. Initially, trees do require an investment of both time and money to provide the desired benefits. Although the biggest cost occurs when trees and shrubs are initially purchased and planted, they also require follow-up watering, pruning and general maintenance. Trees in a natural forest do not require constant care and maintenance to survive. The most healthy forest trees established themselves in natural areas where they were neglected by people. Why then, do urban trees need additional care to survive? Urban trees need additional care because they lack Tennessee Master Gardener Handbook 245