Cooperative Extension

Cooperative Extension College of Agriculture & Home Economics Washington State University Pullman Washington Introduction People use landscape plantings for various purposes. They may plant to join or to separate landscape spaces, to enhance the value and appearance of homes or buildings, to produce fruits and vegetables, to shade an area or cut the wind, or to provide for aesthetics and general well-being. Develop a plan before planting. You will want to place the correct plant properly to create the desired design effect and environmental conditions. Take into account plant needs, such as exposure, amount of light, soil moisture, ph, and drainage. Woody landscape plants should last for many years. Most health-threatening problems which affect landscape plants occur when plants are stressed by use of improper cultural practices. In some cases, the effect of poor cultural practices may not be seen for years. Of all the cultural practices, those associated with improper planting have probably killed more landscape plants than anything else. For example, a tree killed by root rot might never have been infected if it had been placed in a planting hole with proper drainage. Many long-standing practices associated with planting trees and shrubs are no longer recommended, because recent studies have shown they are either an unnecessary expense or are detrimental to plant growth and establishment. You may purchase woody plants that have bare roots, are balled and burlapped, or grown in containers. Transplants of bedding plants and vegetables are usually grown in an organic medium, without soil, in flats, partitioned plastic trays, connected mini-pots, or small,

Bare-Root Plants individual containers. Each plant, however packaged, needs special attention at planting time if it is to grow well and become a part of the landscape. These are mostly deciduous plants which have been dug without attached soil. Many shade trees, fruit trees, and flowering shrubs are sold in this manner. It is essential to keep the root system moist until planting. This may be accomplished by soaking the roots in water for 1 to 2 hours, but for NO MORE THAN 6 hours; by wrapping them in moist burlap; or by temporarily planting (heeling in) to planting depth in moist sawdust, bark or soil. For best results, hold plants in the shade prior to planting. If the roots dry out, the plant's chances for success will be greatly diminished. Before planting, prune back any badly bruised, broken, or jagged roots to sound wood with a clean cut. Girdling roots (major roots which cross over the root system close to the trunk of the plant) may eventually strangle (girdle) the stem. Remove these and any badly kinked roots at transplant time. Dig the planting hole deep enough so the plant, when set in the hole, will be at the level it was in the nursery, or preferably, 1 to 2 inches higher (Fig. 1). The diameter of the hole should allow spreading the roots without crowding or bending them. Backfill using the native soil, which was dug out of the hole. 1 2 Fig. 1. Planting a bare-root tree or shrub. Dig the hole large enough to accommodate the root system, slightly larger is more desirable Place the tree or shrub in the planting hole so it is AT the level it was grown in the nursery or slightly higher. A cone of soil at the center of the planting hole may achieve this 3 Backfill using native soil 4 5 6 Construct a basin to retain water. Water immediately after planting. A mulch can be used to conserve water. Wrap the tree trunk for the first year or two to prevent bark scald

Adding organic amendments to the backfill soil has been a source of controversy and is still found in many planting and transplanting recommendations. Recent research at a number of universities has shown that the addition of large amounts of organic matter (peat moss, compost, ground bark, etc.) does not improve plant growth and may actually have a detrimental effect. If the plant is to be planted in a highly compacted soil, the addition of organic matter to the planting hole may create a constantly wet condition, leading to root rots, or it may create an ideal condition which the roots will never leave. The greater the difference between the structure and texture of the soil in the planting hole and that of the native soil, the greater the possibility of problems. Amending the backfill soil for the planting hole with organic matter is not generally conducive to good root growth. Amending the soil over a large area, such as an entire bed or border, is beneficial for good root growth. This can be accomplished by spreading 2 to 4 inches of organic matter (bark, sawdust, compost) over the area to be planted. The organic matter should then be worked into the soil to a depth of 6 or more inches. The deeper the organic matter is incorporated the deeper will be root development. If a number of ericacious plants (members of the heath family, such as heath, heather, rhododendron, azaleas, etc.) are to be planted in close proximity to each other, it would be advisable to use this system, especially in poor or compacted mineral soils. Construct a basin around the periphery of the planting hole, so that water drains away from the trunk but not away from the root system (Fig. 1). Water the plant immediately to settle the soil and to eliminate any air pockets. Keep the newly installed plant moist but not soggy wet. After the plant is fully established, you may level the basin. Wrapping trunks of newly planted trees may lessen the incidence of sun scald. It is critically important that any fabric or material wrapped around the trunk be white or very light in color, and that the material breathes or allows free exchange of air through the material. Solid plastic type materials increase the incidence of stem cankers and other diseases. Inspect the wrapping every month or so to be certain it is not girdling (strangling) the stem. Where drainage is a problem, it may be advisable to construct a planting berm. This consists of placing the plants above grade, either partially or totally above ground, and filling in around the plant(s) with soil.

Staking at this point will be necessary only if the plant cannot stand by itself. Drive two wooden stakes into firm ground and tie the tree to the stakes with nonchafing material (Fig. 2). Inspect frequently, and remove stakes as soon as the root system is firmly anchored into the soil, usually one growing season. Fig. 2. Staking. Support a landscape plant by driving two stakes into firm ground, making them parallel with the plant and each other (A), so that stakes and tree line up perpendicular to the prevailing wind. (B) Top view. Remove stakes as SOON as the plant is firmly anchored. Balled and Burlapped Plants These are plants grown in the field and dug with a ball of soil around the roots. The soil is wrapped with natural burlap, which will decompose with time, or with synthetic "burlap" (usually polypropylene) which neither decomposes nor allows much root or water penetration. The burlap (natural or synthetic) is held on the root ball with twine or is pinned in place with nails. Do not let the root system of the plant dry out. Hard-to-wet synthetic wrapping materials make watering difficult. 1 2 Fig. 3. Planting a balled and burlapped plant. Dig the planting hole extra wide Deep enough so that when the plant is set into the hole it is at the level it was in the nursery or slightly higher 3 Backfill using native soil 4 Create a basin to retain water 5 If the soil around the root system differs greatly from the native soil, gently fork some of the soil off the root ball and expose the roots (5, dashed line).

Dig the planting hole deep enough so the top of the root ball (as it was grown in the nursery) is at the soil line or preferably 1 to 2 inches higher than the native soil level when the plant is placed in the hole (Fig. 3). The planting hole diameter should be at least twice the diameter of the root ball. When working with plants that have large root balls, make the planting hole at least 1 foot in diameter larger than the root ball diameter. REMOVE ALL STRINGS AND TWINE to eliminate the possibility of girdling the roots or stems. This includes natural materials such as binder twine and hay rope. Cut natural burlap away from the root ball and fold it into the planting hole before backfilling. Synthetic materials used for wrapping the root ball must be cut away and discarded after the plant is placed in the planting hole and before backfilling. Backfill using native soil. Construct a water basin, as suggested for bare-root plants, and water the plant immediately after planting. At times, the soil in which the plant was grown differs greatly from the soil where it will be transplanted. That is, the native soil may be quite sandy, while the soil around the roots may be heavier (more clay). The interface where the native lighter soil (sandy) and the heavier nursery soil meet may pose a barrier to water movement. This generally means the root ball will be constantly dry, leading to a dried out (desiccated) plant; or the planting hole will be constantly wet, increasing the incidence of root rots. If large differences in soil types exist, gently fork soil away from the root system, exposing some of the roots (Dashed line, Fig. 3, number 5). Clean-cut any poorly cut, broken or damaged roots, and backfill with native soil. You can avoid many future problems by placing roots in contact with native soil so they must grow into the soil. Container-Grown Plants Plants grown in containers pose special planting problems. Nursery culture dictates that the plants must be grown in soilless, or organic, medium. When you select a container-grown plant, remove the container and look for fibrous (small) roots growing to the edge of the container, which hold the soil ball firmly together (Fig. 4). Spread the roots (Fig. 5) when transplanting.

Fig. 4. A good root system on a container-grown plant. Fig. 5. Spreading the root system of a container-grown plant. Dig the planting hole deep enough so the bottom of the root ball rests on the bottom of the hole when the top of the root mass is AT or slightly ABOVE the soil line. The planting hole diameter should be dug as described for balled and burlapped plants. Carefully spread the roots while backfilling using native soil (Fig. 6). If the roots are woody, cut or slash them using an old knife, spade, or shovel (Fig. 7). Make six to eight shallow vertical cuts into the root ball, slashing through the exterior woody roots. Use your fingers to loosen the cut roots and spread them away from the container medium. Plant as described above and backfill using native soil. Be sure to keep the roots spread as you fill the hole. Fig. 6. Container-grown plant in planting hole. Roots are spread and hole is partially backfilled. The planting hole

should be larger than the extent of the spread-out root system. Backfill using the native soil. Spread the roots when backfilling. Fig. 7. Slashing a plant root system with circling roots. Make six to eight vertical cuts through the surface roots and spread cut root ends when planting. If roots were not slashed before planting, this plant could develop severe girdling roots similar to those in Fig. 11. An alternative is to "butterfly" the root ball once it is out of the container. This works especially well when the circling roots are very woody. In this procedure, drive a spade or shovel straight through the bottom third to half of the root mass, creating two flaps of the bottom portion of the root ball (Fig. 8, 9). Make six to eight vertical cuts on the top portion of the root ball, cutting through any circling roots.

Fig. 8. Butterflying a container-grown plant root system. Drive a spade or shovel straight through the bottom half of the root system. Make six to eight vertical cuts through the surface roots on the top half of the root system. Fig. 9. A butterflied root system. Two flaps of roots were created by using a spade cut, as in Fig. 8. The top portion of the root system was cut by vertical knife slashes. When planting, spread the two flaps butterfly fashion and place them in the planting hole (Fig. 10). The top of the root mass should be AT or, preferably, slightly ABOVE the soil line. Backfill using native soil, making certain that the cut roots are spread when adding backfill to the planting hole.

Spreading and keeping flaps apart may be difficult. Working a stone, stick, or other piece of wood, or even soil, between flaps to keep them separated may be necessary. Circling roots of container-grown plants that are not corrected before planting will continue to grow in a circle, eventually girdling themselves (Figs. 11, 12). These circling and girdling roots will place severe physiological and mechanical stresses on the plant. The plant will grow poorly, and it may, as in the case of the pine tree in Fig. 11, eventually die. This underground cause of plant stress is difficult, if not impossible, to detect once the plant is in the soil. Fig. 10. A container plant butterflied and slashed. Cut roots at the top of the root system are spread out into the backfill. Fig. 11. The root system, at left, of a 12-year-old shore pine (Pinus contorta) which died slowly after attaining a height of 5 feet. The roots were not cut, spread or butterflied at the time of planting. The roots eventually girdled themselves, killing the tree.

Fig. 12. Bottom of pine in Fig. 11. The pine was planted in the ground from a 1-gallon container. Twelve years later, its root system still fits a 1-gallon container. Field Potted Plants These field-grown plants are dug either with bare roots or with soil, and placed in containers. If the plants are in papier-mache' pots, remove all or at least the top portion of the pot AFTER the plant is in the hole, because these pots may restrict root growth into the native soil. Otherwise, plant as a container-grown plant. Bedding Plants, Vegetable Transplants, Small Perennial Plants Starter plants that help gardeners get the jump on the season usually have a relatively small root mass. They are grown in a highly organic medium in various types of containers, such as flats, trays, or peat pots. At planting, remove plastic containers, and at least the top portion of peat pots. When transplanting these plants, even the annual types, spread the roots so they have good contact with the native mineral soil in which the plant roots must grow. Keep the root system moist, but not soggy wet, until the plants are well established. Pruning the Top at Planting Time Limit this practice to: 1. Removal of dead and diseased branches; 2. Removal of rubbing, interfering, and wrongly placed branches; and 3. Pruning to the desired shape. Begin to select the main skeletal branches (framework) of trees at this point. Planning and shaping the plant when it is small will avoid the need to prune much larger limbs later. Most landscape plants do not require pruning at transplant. It is NOT necessary to remove one-fourth to one-third of the top unless the plant is in full leaf or soft growth when it is dug.

WSU Research Horticulturist, WSU Puyallup. College of Agriculture and Home Economics Washington State University Cooperative Extension bulletins contain material written and produced for public distribution. You may reprint written material, provided you do not use it to endorse a commercial product. Please reference by title and credit Washington State University Cooperative Extension. Issued by Washington State University Cooperative Extension and the U.S. Department of Agriculture in furtherance of the Acts of May 8 and June 30, 1914. Cooperative Extension programs and policies are consistent with federal and state laws and regulations on nondiscrimination regarding race, color, national origin, religion, gender, age, disability, and sexual orientation. Evidence of noncompliance may be reported through your local Cooperative Extension office. Trade names have been used to simplify information; no endorsement is intended. Revised July 1994. Reprinted August 1995. Subject code 255. A Helping You Put Knowledge To Work