Where to Establish a Rain Garden How to Plant a Rain Garden For more information, contact:Locate a rain garden to intercept runoff from roofs,yards, drives, or streets. (Figure 2) It should notbe built within 10 feet of foundation walls or on Use potted or bare root plants rather than seeds. Plant from April to September. Place the more water tolerant species near the bottom, and ♦ ♦ USDA Natural Resources Conservation Service Soil and Water Conservation Districts Rain Gardens ♦ Land Grant Universities and Cooperativepoorly drained sites. A rain garden should not be drought tolerant near the edges. Plant spacing Extension Servicebuilt over buried utilities or where mature plants will vary depending upon species and desired ♦ Local Greenhouses and Nurseriescould obstruct overhead utilities or drivers’ vision. appearance. Generally, 15-18 inches betweenDo not construct a rain garden where prohibited by plants is adequate. Consider mature size whenlocal ordinances or where subject to disturbance. spacing plants. References and Additional Reading* “Living Landscapes in North Dakota: A GUIDE TO NATIVE PLANTSCAPING” Available at North Dakota How to Build a Rain Garden NRCS offices. Booklet contains detailed information on site CapturingMost rain gardens can be constructed withequipment available to homeowners such as evaluation, planning, and establishment of native plants. Adapted forbs, grasses, trees, and shrubs and Using theshovels, rakes, and rototillers. A small rain garden are listed and described.of simple design can be built in a day. Rains of the• Do your homework first. Many design manuals “Rain Gardens - A how-to manual for are available, online and at public offices. Several are listed in the reference section of homeowners” http://www.dnr.wisconsin.gov/org/water/wm/dsfm/ Great Plains this publication. shore/documents/rgmanual.pdf• Locate a proper site. This is an easy to follow manual that shows homeowners how to plan, install, and maintain a• Calculate square footage draining to the rain garden (from roof, yard, drive, etc.). rain garden. Indiangrass• Mark outline of rain garden. Rain garden area “Rain Gardens, should equal about 10% of the drainage area. Figure 5. For much of the summer in the Great Plains, a rain garden might be the only “green” area in a non-irrigated Rice Creek Watershed District.” Irregular margins are often more attractive. http://ricecreek.org/bluethumb/raingardens (Figure 3) yard. This Minnesota web site has information on• Evaluate soil compaction, texture, and creating and planting rain gardens and more. A infiltration. What to Plant in a Rain Garden very effective plant selector tool is part of this site.• Dig a 4-8 inch deep basin with a flat bottom. Rain gardens can be planted to native or Excavated material can be placed on the non-native species of flowers, grasses, shrubs, and Maplewood, Minnesota “Rain Water Gardens” downhill side or moved offsite. (Figure 4) http://tinyurl.com/2yvxxa trees. Do not plant species considered invasive. Avoid compaction during construction. The rain garden program at Maplewood is Consider the growth habit and mature size of the• Loosen 6-12 inches of the natural soil below explained. Pictures and designs of many different species. Some native species are deep rooting and the bottom of the rain garden. garden types are included. Links within the encourage infiltration of runoff water. Native Prairie Coneflower• Large designs or sites with high clay content document give complete details from design species are adapted to local conditions and may be soils may require over-digging the basin 1-2 through maintenance. Blanketflower more tolerant of diseases and drought, compared feet deep, backfilling with a well blended mix of to some non-native species. A diversity of plant 70% sand and 30% organic matter (yard *Note: When using these references, select only species will provide an array of color and texture, compost, purchased peat moss, etc.), and plant species adapted to shaping the top of this material into a 4-8 inch and attract a variety of insects and wildlife. your location. deep basin. Disease and insects may destroy an entire rain garden if planted to a single species. Plants• Slope and pack any created berms, leaving a gentle slope that will be easy to maintain. requiring constant moisture should not be planted Buried pipes and cables can kill in a rain garden. Use locally adapted species and Check with a utility location service or electric,• Smooth, seed berm, and plant the rain garden. varieties. gas, phone, or cable suppliers to locate buried Blue Fescue Bleeding Heart• Apply shredded wood mulch as desired to utilities that may be affected by construction. conserve water and control weeds. Shredded How to Maintain a Rain Garden Some buried utilities are quite shallow and easily mulch stays in place better than wood chips. severed by a hand shovel, causing death or injury.• Water and weed to establish plants. Very little additional water or weeding is needed CHECK BEFORE DIGGING! once a rain garden is established. Supplemental North Dakota water is usually needed only to establish plants and during drought. Apply and renew mulch as By: Craig Stange, Forester, Ecological Sciences Staff Nancy Jensen, Agronomist, Plant Materials Center needed to control weeds and conserve water. USDA-NRCS, Bismarck, North Dakota Chec king Checking Leave vegetation standing over winter for snow depth w ith a wi catch, textural diversity, and visual interest. In April 2007 carpen ter’s carpent early spring, remove previous year’s growth by All programs and services are offered on a nondiscriminatory basis. Helping People Help the Land le vel lev mowing or clipping before new growth initiates.
Figure 3. Plan View of Rain Garden Rain Gardens Buried down- from spout extension “Thought to Bloom” from building Natural Read a good “how to” ground manual (See references) Splash block of e inlet Check local ordinances un c R urfa or rocks f Shredded Check for utilities S wood mulch Locate potential site Perennial Determine size plants Draw a plan Outline the area on the ground Natural Build the rain garden ground outlet Plant the rain garden (overflow) Apply shredded wood mulch 2-3” deep before or after planting Water and weed as Dense upright grass filter strip needed Enjoy the ever changing array of Down- colors and textures from stream spring to fall berm (fill)Figure 1. A 200-square foot rain garden blooms just 2 months after construction and planting. What is a Rain Garden Why Plant a Rain Garden A rain garden is a colorful, perennial planting A Rain Garden designed to capture and use rain water that may ♦ Captures and filters runoff otherwise run off. (Figure 1) It is a garden in a Figure 4. Cross-section of Rain Garden Limited rains of the Great Plains fall hard and Top of berm - shallow depression. It can be large or small. A fast. Runoff from roofs, lawns, and drives may 2-3’ wide, 3” + higher than rain garden is not a wetland and should not hold overload storm sewers and pollute streams. Rain garden natural ground outlet water for more than a few hours, or a day at most. basin 4-8” deep (Figure 2) Natural ground inlet and overflow. It is not a breeding ground for mosquitoes. Berm - Constructed ♦ Reduces the need for supplemental water Surplus water should bypass rain of material from rain Water is often limited in the Great Plains. garden on natural ground, not over garden basin Maintaining a green and colorful yard with rural berms. or municipal water can be expensive. ♦ Grows healthy plants using good water <2 0% Rain is high quality water, good for plants; slop e while well water may be poor for plant health. ♦ Provides changing colors and textures A mix of plants changes color, structure, shape, and form throughout the season. (Figure 5) ♦ Provides habitat Forbs and grasses in a rain garden are attractive to butterflies, bees, birds, and other wildlife. Optional drain tile for very Same grass Optional - Well-blended large runoff or extremely Bottom soil Original Same grassFigure 2. A new rain garden captures roof and yard runoff as rest of 70% sand, 30% organic heavy clay sites; must outlet loosened soil surface as rest offrom a ½ inch, 15-minute prairie thunderstorm in July. Note lawn matter to a 6-24” depth to storm sewer, curb, etc. 6-12” deep lawnthe drought stressed yard outside the rain garden.
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