Rain Gardens

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Rain Gardens

• Landscaping for water quality
• Presented by the Soil and Water Conservation
  District of Lake County

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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

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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

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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

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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

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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

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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
• Dont 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

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Location
Picture courtesy of Wisconsin DNR
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Location
Picture courtesy of Wisconsin DNR
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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

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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

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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

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Determining slope
Picture courtesy of Wisconsin DNR
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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.

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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

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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 carpenters level

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Building Your Garden
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Building Your Garden
Picture courtesy of Wisconsin DNR
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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

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Building Your Garden
Picture courtesy of Wisconsin DNR
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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 dont require
  fertilizer and pesticides

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Root system of the prairie grasses
Picture Courtesy of Chicago Wilderness
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Plants for full sun
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Plants for full sun
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Plants for partial shade
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Plants for shady areas
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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

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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

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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

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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

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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

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Rain Barrels
Picture Courtesy of www.rainbarrelguide.com
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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

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Rain gardens
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Rain gardens
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Questions ???