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CHARLES RIVER WATERSHED ASSOCIATION

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Education and Outreach

How To Plant A Rain Garden

Rain gardens are carefully engineered, but you don’t need to be an engineer to build one! Follow these basic steps and consult the additional resources at below and you can enjoy your very own rain garden for years to come. Below is a list of supplies and tools you will need. raingardenapp.pngThe rain garden icon next to a step indicates that tools, videos or more information can be found on the free Rain Garden App by UConn Clear available from the App Store or Google Play. Building a rain garden is a simple and rewarding task that will improve your own property and the natural environment.

Supplies
Rain garden plants
• Soil and/or compost
• Downspout extender (optional)
• Stones (optional)
Tools
• Measuring tape
• Shovel and trowel
• Hose or bucket
• Gardening gloves
• Rototiller (optional)

Step 1: Chose Your Site

Identifying a spot for your rain garden:
  1. Select an area that can collect water from your roof or driveway.
  2. Sites should be near a downspout to collect roof runoff or downhill of your driveway to collect runoff from it.
  3. Avoid steep slopes, rocky areas and areas that often puddle.
  4. Set your rain garden about 10 feet away from your foundation and direct any overflow away from the foundation.
  5. Check your soil to ensure it will infiltrate water (See step 3).
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Step 2: Design the Garden

Sizing a rain garden to hold runoff from a one inch rain storm is a good target, although smaller rain gardens can still make a big difference.

Ideal size for your garden:
Rain Garden AppMeasure the area (length x width) of the roof or driveway that your rain garden will collect water from in square feet and then divide by 6. This gives you the target size for your rain garden in square feet.

Selecting Plants
  • Rain GardenA rain garden best supports plants that can tolerate both wet and very dry conditions.
  • Native plants are well adapted to local conditions and will provide habitat for birds, butterflies and other wildlife. Edible plants should be avoided.
  • Determine whether your garden is in the sun or shade.
  • Consider during which season the plants will bloom and how they will look together in the garden.
  • Keep in mind each plant’s mature size and plan for future growth.

    Visit UConn's rain garden plants for a complete list of possible plants for your garden.

Step 3: Prepare the Ground

  1. Always call 811 before you start digging to avoid disturbing buried utility lines
  2. Rain Garden AppConduct a soil infiltration test described below. Based on results you may need to add some potting soil to your rain garden.
  3. Do not add fertilizer. Fertilizer will make it harder for the rain garden to do its job

Soil Water Infiltration Test

  1. infiltrationMark out the area where you will build your garden
  2. Dig a hole 6-8 inches deep and 6-8 inches in diameter at the location
    you chose for your rain garden
  3. Fill the hole with water
  4. Time how long it takes for the water to soak into the ground
    • If your site is able to infiltrate water in less than 6 hours, use the soil you excavate mixed with some compost as the planting medium for your rain garden. you can also size your garden somewhat smaller, dividing the drainage area by 12instead of 6 to determine the square footage of your garden.
    • If your site takes 6-24 hours, use garden soil from a garden center as the planting medium.
    • If it takes more than 24 hours for water to soak in, select another site.
    • Do not add fertilizer! Fertilizer will make it harder for the rain garden to filter out pollutants.

Step 4: Landscape the Garden

Landscape Suggestions
  • dig your gardenGarden edges can be sloped or vertical.
    • If the garden edge is vertical, consider reinforcing with edging stones.
  • If directing stormwater into your garden via a downspout, position the outlet in the garden and add stones around the opening to help slow the water and avoid erosion, being careful not to block the outlet.
  • Lay out the plants in the garden. Avoid blockinglight from reaching short plants by placing them too close to taller plants.
  • For a great looking garden, group plants in odd numbers, and avoid planting in straight lines.  
    • Each hole should be as deep and twice as wide as the plant’s root structure. If the plants are root-bound, try to loosen up the roots before planting them. 

Step 5: Maintain Your Garden

  • For the first 1-3 months, your new rain garden will need extra care. When it does not rain, water your garden once a week with 1 inch of water (about half a gallon of water per square foot). After the plants have been established, you no longer need to water your garden.
  • Weed your garden regularly, especially during the first couple of months. As the plants age, remove any dead branches or plants and prune shrubs and trees as desired. Check the areas where water enters and exits the garden for signs of erosion. Fix any problems and add additional stones if necessary.
  • Check the garden to see if it is collecting dirt, sand or other debris and shovel out as necessary. If your property changes hands, make sure to inform the new owner about the special value and function of the rain garden.

Learn More

Rain Garden Demonstration 

About Rain Gardens

About Education and Outreach

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