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Downpour Gardens

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  1. Rain Gardens Landscaping for water quality Presented by the Soil and Water Conservation District of Lake County

  2. What is a rain garden? • A rain garden is a shallow depression in your yard that is planted with native flowers and grasses • It is positioned in the yard to receive runoff from your roof, sidewalks, driveway and lawns allowing water to slowly soak into the ground

  3. Rain gardens – a short history • Rain gardens are a relatively new concept • They emerged in 1993 in Maryland out of the need for low cost stormwater infiltration methods that would improve water quality • The idea of bioretention or holding and filtering stormwater in plant systems came about • The term was later refined as rain gardens as it was more attractive • Since then, the concept of rain gardens has been developed by other states especially Minnesota, Michigan and Wisconsin • A more widespread use of such gardens could dramatically improve water quality everywhere

  4. Why are they important? • The conversion of land from forests, grassland and agricultural land to urban and suburban lots has reduced the natural ability rain water to infiltrate into the ground because of increased impervious surfaces • This results in stormwater runoff that carries pollutants from streets, parking lots and lawns into our local lakes and streams, degrading their water quality

  5. Green Infrastructure: A Strategic Approach to Natural Resource Planning and Conservation Why are they important? Urban areas are spreading rapidly... • Chicago (1970-1990)… • 288,000 acres converted • 35% increase in developed land • 4 % increase in population

  6. Why are they important? • One way we can improve water quality right on our own properties, is by planting rain gardens, that can filter and re-direct rain water • Even though they are small in size, collectively they can make a big difference

  7. Rain Garden Basics • Location • Your rain garden should be at least 10 feet away from your house • It can be placed close to your downspout so it only receives water from the roof • Or further away so it catches water from your roof and your lawn • Don’t put it where water already ponds – the idea is to encourage infiltration • Plants will grow easier in full sun than in shade or under a tree • A flat area of the yard will be easier to dig than on a slope

  8. Location Picture courtesy of Wisconsin DNR

  9. Location Picture courtesy of Wisconsin DNR

  10. Rain Garden Basics • Size • You should choose a garden size that you can manage; typical sizes are between 100 and 300 sq.ft. • The depth can vary between 4 and 8 inches • A garden that is too small and too shallow will not have enough plant variety and will not provide appropriate infiltration • Similarly a garden that is too large and too deep will be hard to maintain, expensive and will resemble a hole in the ground filled with water

  11. Rain Garden Basics • Size • To find the perfect size for your garden take into considerations a few things: • Soil types • Drainage area that will feed into the garden • Depth of garden • Clayey soils drain slower that sandy and silty • The bigger the drain area, the bigger the garden should be • Depth of garden should be determined by the slope of the lawn

  12. Rain Garden Basics • Determine soil type • The soaking test • The ribbon test • Determine the drainage area of your property • For gardens less than 30 feet from downspout • For gardens more than 30 feet from downspout • Determine the depth of the rain garden by determining the slope of the lawn

  13. Determining slope Picture courtesy of Wisconsin DNR

  14. Rain Garden Size • Having determined soil types, drainage area and depth, you can now calculate the surface area of your garden • Use the table below to do that • Find the size factor for the soil type and rain garden depth. • Multiply the size factor by the drainage area. This number is the recommended rain garden area. • If the recommended rain garden area is much more than 300 square feet, divide it into smaller rain gardens.

  15. Building Your Garden • Anytime before digging in your garden you should call JULIE (Joint Utility Locating Information for Excavators) at 1 800 892-0123 • Recruit some friends to help you out so the work will take less time • Do some advanced prep work to lighten up the physical load

  16. Building Your Garden • Start out by defining the shape of the garden with a string or a flexible hose • While you dig put the soil outside of the string; you will use the displaced soil to build a berm or a low wall • If you are on an incline start out at the high end and work your way towards the low end; make sure you know how deep your garden has to be • When you are done digging check to see that the bottom of your garden is flat; you can “eyeball it” or use a 2x4 and a carpenter’s level

  17. Building Your Garden Picture courtesy of Wisconsin DNR

  18. Building Your Garden Picture courtesy of Wisconsin DNR

  19. Building Your Garden • If your lawn has a slope greater then 8% you will need to use some of the soil you dig to level the garden • The rest of the soil will be used to build the berm • When you are done digging, rake the soil smooth and prepare for planting • For better plant establishment compost can be used; you can mix it with your soil

  20. Building Your Garden Picture courtesy of Wisconsin DNR

  21. Choosing plants • You should choose plants based on the sun/shade pattern and soil type to ensure proper growth • Native plants is they way to go due to their resilience and low maintenance needs • They come in different varieties and colors, they are drought resistant and they don’t require fertilizer and pesticides

  22. Root system of the prairie grasses Picture Courtesy of Chicago Wilderness

  23. Plants for full sun

  24. Plants for full sun

  25. Plants for partial shade

  26. Plants for shady areas

  27. Planting • You should come up with a pleasing design keeping in mind the height of the plants and color variation • Clump plants together for a visually enjoying display • Do not exclude the rest of your property – plan the rain garden as part of a whole • Native plants should be planted about 1 foot apart to allow roots to grow well • As soon as you finish mulch and water

  28. Maintenance • The first year after planting your rain garden is very important in terms of maintenance • It will determine how well your garden will do in the future • Two key components are watering and weeding • Second component cannot be emphasized enough since the plants and weeds are in powerful competition for resources • Once the garden is established (typically it takes 2-3 years for complete establishment) the amount of maintenance will reduce considerably

  29. Alternative to Rain Gardens • If you feel that installing a rain garden is too much work, you can take advantage of rain barrels • They collect rain water from your roofs, which can be used for irrigation later • It is a cheap, easy alternative and requires no maintenance

  30. Rain Barrels • Residential irrigation can account for 40% of domestic water consumption in a given municipality • Rain barrels not only store water, they help decrease demand during the times when precipitation is scarce • Only 1/4 inch of rainfall runoff from the average roof will completely fill the typical barrel

  31. Rain Barrels • Rain water is ideal for watering your gardens because it tends to have fewer sediments and dissolved salts than municipal water • Saving water in this manner will reduce your demand for treated tap water, and save money by lowering your monthly bill

  32. Rain Barrels Picture Courtesy of

  33. Resources • One of the best resources is the booklet I used for this presentation “Rain Gardens – A How To Manual For Homeowners • The Soil and Water Conservation District of Lake County can help answering any questions about native plants • Also Applied Ecological Services can help with designs and planting ideas

  34. Rain gardens

  35. Rain gardens

  36. Questions ???