Rain gardens are a great way to help better manage storm water and runoff.  These gardens will help you reduce water runoff from your site, help filter the water going into the ground, and improve the aesthetics of the property.


  • Call Iowa One Call 1-800-292-8989 to locate all utilities.
  • Make sure the area for your rain garden is NOT over a septic system and that it is at least 20’ away from a building with a basement and 10’ away from a building with no basement.
  • Dig a hole one foot deep and fill it with water.  If the water has not completely drained within 48 hrs this site is not suitable for a rain garden.
  • Make sure the slope of the ground is less than 12% if possible.
  • Measure the size of the area that will be draining into the rain garden. (example the square feet of the roof draining out of the down spout to the garden, or the square feet of driveway that will be draining into the garden) To determine the size of garden you need multiply that number by 20% if your soil is sandy, 30% if you have a loam soil, and 50% if you have a clay soil.  This will give you the size of bed area you will need in square feet.


  • Measure out the shape of the bed with a paint line.
  • Dig out the soil to a depth of 8”-9”.  Some gardens can be dug up to a depth of 1’-2’.
  • If the garden is built on a slope, construct a berm on the downhill side of the rain garden so that the perimeter of the rain garden is level from front to back and side to side.
  • Make sure the bottom of the garden is flat and level.  DO NOT DRIVE EQUIPMENT OVER GARDEN AREA AND LIMIT THE AMOUNT OF WALKING ON THE AREA.
  • Fill the area back in with a 40% soil from the site, 60% compost mix.  In areas with extreme clay increase the amount of compost in the mix.
  • Level the fill.
  • Plant native plants in the rain garden for the best results.  Listed below are 10 excellent choices for a rain garden.
  • Add a 2”-3” layer of shredded hardwood mulch.
  • Overseed the berm on the downhill side of the rain garden and cover with erosion control blanket.
  • Water plants every other day for the first two weeks if there is no rain.  Do not add any fertilizer or herbicides if at all possible.



Common Name

Scientific Name

Swamp Milkweed

Asclepias incarnate

New England Aster

Aster novae-angliae

Brown Fox Sedge

Carex vulpinoidea


Chelone glabra

Spotted Joe Pye Weed

Eupatorium maculatum

Common Sneezeweed

Helenium autumnale

Blue Flag Iris

Iris virginica var. shrevei

Spike Blazing Star

Liatris spicata

Swith Grass

Panicum virgatum

Mountain Mint

Pycnanthemum virginianum








  • In the fall cut dead perennials back to several inches.  Leave the grasses.
  • Cut back grasses in the spring and topdress mulch with 1” of fresh mulch.
  • During the growing season regularly weed the rain garden.


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