Caring for a Native Garden

Transcription

1 Roots Neighborhood Habitat Caring for a Native Garden Illinois Department of Natural Resources Coastal Management Program

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3 Why Garden with Native Plants? Why is a Roots Neighborhood Habitat garden important to everyone? Lots of reasons: less pollution, less waste, less stormwater runoff, something nice to look at, more birds hanging around and singing. Speaking of birds, let s look at a typical city block in Chicago and what a bird sees when it flies over. 38% of the ground is covered in pavement. Another 24% is covered with buildings. That leaves 38% of the land open for plants, animals, and you. Most of that land is covered by mowed lawn. Less than 1% has vegetable and ornamental gardens. Mowed lawns are great surfaces to run on and play on. Yet from nature s point of view, a lawn does not do much. Birds flying overhead will find very little to eat. There are no fruit-bearing plants, and if the lawn is mowed there will not be much seed either. But for most birds, the food source is insects. A lawn might offer the occasional cricket or grasshopper, but not much else. Native plants provide plenty of food. Most wildflowers and grasses will support a few species of insects, as well as provide nectar for butterflies and other pollinators. Group a lot of native plants together and you start to get a variety of foods for different animals. Shrubs and trees provide even more meals. For example, oak trees provide food for over 700 species of insects, birds, and mammals. Many non-native plants do well in gardens but don t provide quality food resources for local insects and birds. Hydrangeas are promoted as attracting butterflies, but provide little nectar and no butterfly caterpillars can eat the foliage. Sometimes garden plants become invasive species. Dame s rocket, first planted as a garden flower, is now invasive in woodlands and along streams. Non-native plants may also pose problems for people. Japanese barberry, a common landscape shrub, creates ideal conditions for ticks to thrive. A native garden is not just for wildlife. Wildflower gardens can help homeowners, neighborhoods, and cities manage pollution and stormwater. Turf grasses come from cool, moist places like mountain meadows where roots don t need to soak up scarce water. They grow a dense mat of shallow roots to catch water as it flows past. Most rainwater that lands on a lawn runs off until it finds the nearest pavement. From there, it flows to the nearest sewer or low spot in the road. Flooding results, especially during heavy rains. In contrast, native plant roots grow deep and wide. They can intertwine with each other, creating a net of roots deep down into the soil, over 10 feet deep in some cases. This ever-growing network keeps soil loose. A mowed lawn is like using a welcome mat to soak up water. A native plant garden is like using a sponge to soak up water. For people, the best benefit to gardens is the effect they have on a community. Gardens help beautify a neighborhood with color and foliage. People tend to gather around gardens to both care for them and admire their beauty. When gardens become focal points of a neighborhood, they become symbols of local pride. 1

4 Location There are several factors to consider when placing a garden. Location is everything. LIGHT The light that a garden location receives will help determine what can grow. Plants used in Roots Neighborhood Habitat gardens are prairie plants which do best when they get light all day long. Most of them can handle a little bit of shade at some point in the day. If you must plant your garden in a spot that gets a bit of shade, end-of-the-day shade that provides relief from summer heat is the best. SLOPE In Chicago, most yards are relatively flat and slope isn t a worry. If you have a sloped yard, avoid picking a garden site at the base of a slope where water pools. Such places are better suited to rain gardens. SOIL A good soil is one that allows water to infiltrate and can hold nutrients. Your backyard will likely have one of three soil types: sandy, clay, or fill. The first two are relics of pre-settlement times. The third is man-made. The sandy soils often found close to Lake Michigan allow water to quickly infiltrate and trickle down. Most have enough organic material to bind nutrients and hold water. Native plants do not require high organic content to prosper; as little as 2% is enough. If you have a sandy soil, you should not need to augment it in any way. Clay soils hold nutrients, but are dense and will keep water from infiltrating. Water usually runs off clay before it seeps in. Most of the native plants selected for the Roots Neighborhood Habitat program will grow in clay soils if seedlings are transplanted there. Clay only poses a problem for seed germination. In some parts of the city, especially the former marshes and wetlands of the South Side, soils contain various types of man-made fill used to elevate the ground level above the wet soils. This dense material does not let water pass through and makes for a poor growing environment. But plants can still find ways to grow on it. The roots of native plants can even help start the process of breaking fill down. If you have a soil made up of fill, placing several inches of topsoil on top is a good way to create a material that can hold moisture and nutrients. 2

5 Preparation Lots of books have been written about how to prepare a garden. We ll skip the book and get to the basics. Tools: Make sure you have the tools you need in advance. Rakes and shovels are obvious. You may also need a hand tiller, especially for a dense soil like clay. Tape measure, string, and stakes are useful for measuring and laying out the plot. Bulb planters are ideal for digging holes for garden plugs. A watering can and a bucket may also come in handy. Finally, don t forget gloves to protect your hands. Three examples of spades, from left to right: a turf spade, for digging up sod-forming grasses; a garden spade, for digging in clay and packed soil; a hand spade, for breaking up lumps in the soil. A garden rake can be used to rake up large leaves and to uproot seedling weeds sprouting in open ground. A tiller (left) is used to break up and turn over soil, and is helpful for breaking up clumps of weeds. A hand tiller, or garden fork (right), serves the same purpose for small patches of soil. A bulb planter is used to dig holes up to 4 inches deep for planting bulbs or seedlings. A dandelion digger is used for digging up weeds that have deep roots. Plan: Lay out your garden in advance. In nature, plants may look like they are randomly arranged. They tend to grow in groups. Arranging plants by groups in a garden is something plants are accustomed to. When figuring out where plants will go, consider their height, their color, and when they bloom. Also consider the garden location. A garden in the middle of the yard may look best with 3

6 tall plants in the middle, surrounded by shorter plants. A garden along a fence or wall may look best with tall plants in the back and short plants in the front. An example of a garden plot layout located in the middle of a yard. An example of a garden plot layout located along the fence line of a yard. Several species of grasses and sedges are included with the plants for Roots Neighborhood Habitat gardens. In nature, grasses are the great equalizer. They provide competition that keeps wildflowers from growing out of control. Space the grasses and sedges equally among the wildflowers. Weeding: If the area where you are planting your garden has weeds, you have several options. You can use an herbicide that will kill everything on the weeds to knock them back. Keep in mind that new weeds will spring up from seeds in the soil, and you may need to do this several times before you are ready to plant. A better option is to install a weed barrier, similar to the method for removing grass from a garden area. See the separate section on weed barriers. Refer to the appendix for more information on weed barriers. Removing Lawn Grass: If you are replacing lawn with a garden, you may be thinking I ve got to dig up how much sod? The answer is none. A weed barrier works just as well on grass as it does on weeds. The barrier should be installed 4 weeks before you intend to put plants in the ground. Refer to the Appendix for more information on weed barriers. Compost: If your soil is a fill soil or heavy clay, 2-4 inches of compost or topsoil will help plants establish. Put the topsoil/compost down several weeks before you plant. Keep it moist so it can settle. Planting on a soil/compost layer before it has settled will result in plantings that are too shallow and prevent roots from anchoring before winter. This can lead to the frozen group pushing plants up and out, which will kill the plants. Mulching: A mulch layer can be put down to help suppress weeds. Basic information about mulching can be found in the appendix that covers weed barriers. 4

7 Time to Plant! Spacing: Most plants should be spaced 12 inches apart, especially if you desire your garden to have a formal look. Some plants can be placed closer together. Plants that spread along the ground, like wild strawberry, can be placed far apart. As they grow they will fill in the spaces. Planting Depth: Live plant plugs, the small plants grown in trays, should be planted so the root crown is level with the surface or slightly above the surface. Plants will usually settle in after being watered a few times. Better to be a bit too high than too deep. Planting Hole: Typically the planting hole should be twice the size of the plant plug. Holes can be dug with a hand trowel or a bulb planter. Before You Fill In: Some gardeners suggest loosening up the roots before putting the plant in the ground. Because these are perennial plants, this step is not necessary. The roots will start growing soon after planting. Not loosening the roots will also reduce the stress the plant experiences when being transplanted. If the plant plug is too deep in the hole, take the plug out and fill in the bottom of the planting hole with loose soil. Tamp it down lightly and check the plant depth again. Keep filling in the bottom of the hole until the plug is at the proper depth. Then fill in around the sides of the plug with soil. Pack the soil lightly so that the plant is firmly in the ground. After You Fill In: Water around the base of the plant. Give the plant enough water so that the soil is wet. If water starts to form puddles, you can stop watering. The watering will help to further settle the soil. If a depression forms in the soil around the plant, fill in around the plug with some extra soil. 5

8 Caring for a Native Garden Now that the plants are in, the fun part begins. Native plant gardens require most of their care and maintenance in the first two years. After that time, plants should be established enough hold their own. By year three, weeding should only be an occasional project as native plants fill in and their roots really begin to spread out. FERTILIZING: is not needed. Native plants may look droopy from the stress of being transplanted, not a lack of food. Plants usually rebound in the second growing season once roots are established. WATERING: In year 1, the garden should be watered moderately (so that the soil is wet but water doesn t puddle) 2-3 times a week during the first 6-8 weeks after planting. Using a watering can to water around the base of each plant is the best watering method. If you are gardening with mulch, make sure the mulch is soaked. Water will trickle and seep to the soil from the mulch when it is soaked. Wet mulch is heavier than dry mulch and will also keep the weed barrier in place. o After a good rain (1/4 inch or more), you won t need to water for hours. o In year 2 and beyond, you should only need to water during periods of extreme heat or drought. When it doubt, it is better to water than not to water. Signs that plants are suffering from lack of water include drooping stems and leaves, yellowing or browning leaves, and flowers that fall off the plant soon after blooming. WEEDS: Weeds will be the biggest challenge in years 1-2. That challenge is bigger in native plant gardens. It will take a beginner time to learn how to tell the difference between native plants and weeds. A leaf guide for plants used in Roots Neighborhood Habitat gardens is available. A wildflower field guide is a helpful reference as well, such as A Field Guide to Wildflowers: Northeastern and North-central North America (Peterson Field Guides). o A bit of common sense can help identify weeds. If you have a hundred of the same plant growing, it s probably a weed. o Pulling weeds can damage roots of your native plants, scatter seeds, or break roots and lead to new weeds. The best way to combat weeds is to cut them at the base, as close to the ground as possible. Use a garden clipper with a sharp blade. A Roots Neighborhood Habitat guide to common weeds in the urban habitat is also available. o If you need help from a plant expert, press a sample of the plant between the pages of an old book, or one you don t mind getting a bit of water damage. After a couple of days, take a picture of the pressed plant against a white background. If you have a garden center or University of Illinois Extension nearby, you can also bring the sample to an expert for identification help. o Corn gluten meal (CGM), typically sold as animal feed, is known to suppress smallseeded weeds while not bothering established plants. Most garden weeds have small seeds and CGM is effective against them. CGM is normally applied in the spring, and it is sold at most lawn and garden supply stores. Check with your local garden supply to see if using CGM would be effective. 6

9 o Some weeds in the area are especially problematic and may require special control methods. Refer to the Roots Neighborhood Habitat guide to common weeds in the urban habitat for more information on these species. MULCH: If you need to apply mulch, avoid burying the tops of your native plants. Use small wood stakes to mark their positions before applying the mulch. You can maintain a mulched garden bed over time if you prefer the look, and the mulch will also help to suppress weeds. A mulch bed can hamper native plants by holding too much moisture and keeping the soil cool. If you do mulch, keep the mulch layer thin, only 1-2 inches. More information on mulching is found in the appendix on weed barriers. Off-Season Care: First Year Having a garden and landscaping with native plants is a great excuse to procrastinate, especially in the first year. As plants die back for the winter, there is very little you need to do. The off-season for a garden in this area is typically November to March. FERTILIZING: is not needed in most cases. If you have a low-quality fill soil, a fertilizer application may help invigorate the plants and promote better growth. A 1-2 mulch layer of manure or compost will be sufficient. Ask a local garden care specialist or your local University of Illinois Extension for advice about your particular soil. REMOVING DEAD PLANT MATERIAL: Leave this in place. Roots can take up to a year to establish, and the dead stems are still attached to the root. Tugging or breaking stems may upset the roots. The first big snow of the year should weigh most of the dead stems down. The material can be removed in the spring. Use a clipper to separate the dead dried stems. WEEDING: Most plants with green leaves in the off-season are probably weeds. If you aren t sure, take a picture and send it to dnr.cmp@illinois.gov. We ll help you ID it. WATERING: The cooler temperatures and fall rains will make any watering unnecessary. MULCHING: This can wait until the spring. If you do plan on mulching, mark the locations of your plants with a small wooden stake. Do not bury the plants under more than 2 inches of mulch. RAKING: if you have leaves blowing into your garden, wait until spring to rake if possible, so as not to uproot plants. If you must rake, try to wait until after the first frost, and rake gently. Off-Season Care: Year Two and Beyond Want to watch a game on Sunday instead of working in the yard? The garden, and the wildlife that uses it, will thank you for it. Native plants will be green from April to October. Here are care tips for those times when the plants are dormant. FERTILIZING: not needed. REMOVING DEAD PLANT MATERIAL: Many of the insects a native garden attracts lay their eggs on plants to spend the winter. This all but guarantees that when the eggs hatch in the spring, 7

10 they ll be near their food source. Dried vegetation, especially grasses, can provide some shelter for birds in winter. Leave the dried stems in place for winter, if possible. In early May, dried stems can be clipped. You can drop the clippings on the ground to return their nutrients to the soil. o In an established garden, some plants may produce seed. Seeds need light and warm soil. Fire guarantees this in natural settings, but as a homeowner you can t burn garden material. If you maintain a weed barrier, native plant seed will also be blocked from germinating. If you do plant seeds from native plants, remove all dead plant material before spreading the seed. This will help the soil warm up in spring and trigger germination. WEEDS: Weeds are hardy. Many stay green after native vegetation has died back. These weeds can be removed. Cut the stems whenever possible; only pull weeds as a last resort. This prevents damage to the roots of native plants. o Many of our weeds are annuals and biennials, meaning they die after flowering. If any weeds have flowered, clip the seed heads and dispose straight to the trash. Seeds of some weeds can live in soil for 30 years or more. Don t leave weed seeds on plants during winter, unless you REALLY like weeding. o If you decide to use corn gluten meal to control weeds, make sure you remove dead material, leaves, and mulch before applying so you can maximize the amount of CGM that reaches the soil. MULCH: If you choose to mulch, choose the right mulch for the job. Windy areas or those prone to flooding should use heavy mulch such as wood chips or bark chips. Mulch keeps weed seeds from germinating. It also keeps native plant seed from germinating. If you re growing things from seed, don t put down a mulch layer. WATERING: Only water in the off-season if you need to keep mulch wet so it doesn t blow away. Too much water can rot away the roots of native plants. RAKING: Leaves may blow in from surrounding trees and shrubs. They block sunlight, keeping soil from warming up and slowing the emergence of native plants and germination of seeds. If gardens need to be raked, do so gently to avoid disturbing the roots of native plants. When the garden is established after 3 years or so, leaves can be left behind over the winter to provide additional shelter for wildlife and insects. Leaves should still be raked in early spring. o If your native garden is made up of shade-loving woodland plants, then raking isn t as important. Any raking is more for aesthetics in this case and can be done at your discretion. 8

11 Other Sources Native Plants Field Guide: Wildflower field guides are inexpensive (usually under $15.00) and have basic information needed to easily identify plants. Field guides with line drawings are recommended. Highlight the pages with the plants in your garden for easy reference. Weeds The University of Illinois Extension offers information on weed identification and control. Many extension offices have gardening and weed experts that can assist with tough questions. 9

12 Roots Neighborhood Habitat Native Garden Timeline YEAR ONE Plan Layout Removing Grass Compost Planting Watering Weeding* Mulching Remove Dead Plants Raking Leaves January- March April May June July August September October- December * Excessively weedy areas should be weeded in a "Year Zero". 10

13 Plan Layout Removing Grass Compost Planting Watering Weeding Mulching Remove Dead Plants Raking Leaves YEAR TWO January- March April May June July August September October- December Plan Layout Removing Grass Compost Planting Watering Weeding Mulching Remove Dead Plants Raking Leaves YEAR THREE AND BEYOND January- March April May June July August September October- December 11

14 Appendix: Installing a Weed Barrier Plants need three things to grow: water, food, and sunlight. Remove one of these three and a plant dies. The idea behind a weed barrier is to cut the plant off from sunlight. Weed barriers use a combination of mulching material to accomplish this. A weed barrier is only effective against any weeds already growing in the soil or from stopping any seeds in the soil from germinating. Any weed seeds that find their way to the top of the weed barrier can still grow. Occasional weeding will still be needed. Weed barriers can also be used to eliminate lawn/grass areas from a yard and make the space suitable for gardening. A major benefit to using a weed barrier instead of turning soil is that a layer of organic material is left behind that helps to enrich the soil for a garden planting. MATERIALS A weed barrier is a combination of two materials: a solid layer of material that sprouting plants cannot penetrate. The solid layer is covered by a porous layer of material that allows water to seep through and helps weigh down the solid layer. It also helps to keep weed seeds from germinating. In a garden setting, use weed barrier materials that allows water to penetrate and soak down into the soil. Paper or cardboard are typical materials, and newspaper is the best to use. Modern newspapers are printed with soy-based inks and are biodegradable. Newspaper is easier to use with an irregularlyshaped space as it doesn t require trimming. Cardboard boxes can also be used, though any packing tape and mailing labels should be removed first. Cardboard is easier to use with large spaces. Do not use plastic; as it does not allow water to penetrate and it holds in too much heat. Because newspaper and cardboard can be blown away by winds, a heavy, porous material should be used to weigh it down. Wood chips work best because they will soak up water. The downside to wood chips is when they break down; they use up nutrients in the soil. Wood chips are also best for new weed barriers. Bark chips, larger chips from the bark of trees, do not take up as much water as wood chips and may not hold down the solid layer as well as wood chips. They do not pose the same nitrogen depletion problems as wood chips. Bark chips are best used for weed barriers in established gardens. Stakes and string can be used to mark off the area the weed barrier is to be installed over. These will make it easier to neatly install the barrier. Stakes can be made from household materials such as disposable chopsticks, sturdy twigs and other repurposed items or you can buy them at your local hardware or garden store. The weed barrier should be in place at least 1 month before the garden is planted for it to be truly effective. The more time you allow the barrier to do the work, the more weeds will die. Lawn grasses set their seed in late spring, and early spring is a good time to install the barrier to prevent seed set. 12

15 Most gardens weeds produce seed in summer, making late spring or early summer a good time to install the barrier. BEFORE YOU INSTALL Whether you are installing a weed barrier to kill grass or weeds, the most important part of installation prep work is making sure the weed barrier is as close to the soil as possible. The area should be mowed as low as possible. A weed whacker gives the shortest cut possible. If the site has any noxious or invasive weeds present (refer to the weed guide for common noxious and invasive weeds), an herbicide application can help to get rid of them. This is especially true for weeds that spread by underground stems such as bindweed and Canada thistle. There should be a 5-7 day wait between the herbicide application and the weed barrier installation. Use garden stakes to mark the edge of the garden area that the weed barrier is to cover. String can be wound around the stakes to better mark the edge line of the barrier. PUTTING DOWN THE WEED BARRIER Installation methods will differ slightly depending on the barrier material. If you are using newspaper, pre-soak it in a bucket of water before putting it down. This is recommended to keep newspaper from blowing away before the top layer is put down. The newspaper layer should be 4-6 pages thick for lawns, 6-8 pages thick for garden weeds. If cardboard is used, a hose can be used to thoroughly wet the cardboard once it is in place. If the cardboard needs to be trimmed, it should be done before it is wetted down. One layer of cardboard is sufficient for lawn or garden weed control. For both newspaper and cardboard, you can use bricks, landscaping stone, or any heavy object to temporarily weigh down the material until the mulch layer is added. MANURE OR COMPOST AS A MULCH LAYER If you are working with a poor quality soil such as a fill site, a 1-2 inch layer of manure or compost will help replenish soil nutrients. Such a layer should not be used as a replacement of a mulch layer. Soil or compost will decompose quickly; exposing the solid barrier to wind that might blow it away. Manure or compost should not be mixed in with mulch layer materials, as some of it will wash away or turn the wood chips into a muddy mess. Manure or compost is best applied underneath the barrier layer. PUTTING DOWN THE POROUS LAYER Regardless of the material to be used, the mulch layer should be at least 2 inches thick. Straw is the least expensive material. It is also the easiest material to work with. Like newspaper or cardboard, it will blow away in strong winds unless it is wet. It helps to moisten the straw in a bucket of water before 13

16 putting it over the solid layer. Straw is also the easiest material for garden plants to penetrate in the spring, allowing for the plants to grow. Wood chips or bark chips do not need to be pre-moistened to install. A shovel will be needed to move the material around. A garden rake is helpful to smooth out the material and create an even layer. Even when dry, these materials should not blow away. How often to water the barrier to keep it weighed down depends on weather conditions. Straw mulch will need to be frequently watered to keep it weighted down, as often as every day during hot dry conditions. Use your own judgment, and err on the side of caution so the mulch isn t scattered all over the neighborhood. Wood chip and bark chip layers will not need to be watered as often as straw. Twice a week is usually sufficient to keep the material weighted down. Again, use your best judgment. If you feel the barrier needs to be watered, give it a watering. LONG-TERM CARE OF WEED BARRIER If cared for properly, the solid weed barrier should be decomposed within a year of installation. The purpose of the solid barrier is to kill off plants that already have established themselves. The barrier blocks sunlight, and therefore the plant s ability to make food to sustain itself. After a year, all established grass or weeds should have long since died off. The long-term purpose of the barrier is to prevent any lingering seeds, or seeds that blow into the garden, from germinating. After the first year, only replacement of the mulch material should be necessary. The material should be laid down at the same 1-2 inches of thickness. When replacing mulch material in an established garden, it is important not to put a thick layer on top of garden plants. That may slow their development or kill them off by burying their base too far below the surface of the soil. To prevent this, the best time to replenish mulch is in the early spring. Using the dead stems from the previous season as markers of the locations of garden plants makes it easy to put the new mulch down. Work the mulch around these stems so it is thickest on open ground, thinnest where the garden plants will be sprouting. The early spring application will prevent the germination of any weed seeds that may be present in the soil. Because a native plant garden does not require much water, straw is the least desirable mulch material for an established garden. Bark chips are the best material because they decompose slowly and are the most porous, allowing water and air to circulate down to the soil. If wood chips are used, they should be a coarse grade, i.e., large pieces instead of small. 14

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18 Printed by authority of the State of Illinois May 5, 2014