Rainscaping Guide: Is a Rain Garden Right For Your Site?

A rain garden is not always the best choice for every landscape. Use the flowchart below to figure out if a rain garden is a good fit for your site. Click on the purple or blue boxes to go to that topic or use the links below the chart for help in examining your site.

Is a Rain Garden Right for Your Site? flowchart

 

Link to Work Wonders with Woodlands section Link to Conquer Compacted Soils section Link to Stabilize Steep Slopes section Link to Let Loose on Low Wet Areas section Link to Design & Build a Rain Garden section Link to How to Conduct a Percolation Test Link to Examine Slopes Link to Woodlands and Rain Gardens section

Conduct a Percolation Test

A percolation test, sometimes referred to as a perc test, determines how quickly water can move through the soil when saturated. The results of a perc test will help determine the suitability of your site for a rain garden.

Dig a hole(s) in the soil 6 inches deep and about 6 inches in diameter. The location of the perc test should be in the center of where you plan on creating a rain garden. Perform the test when the surrounding soil is saturated, such as the day after a rain. If there has been no rainfall prior to the test, fill the hole with water, and thoroughly saturate the surrounding soil with a hose. Wait for the hole to drain, and fill the hole(s) to the top a second time. Check the hole again in 24 hours and if the water is all gone you are good to go because the minimum percolation rate that is suitable for a rain garden is .25 inches per hour (6 inches divided by 24 hours = .25 inches per hour).

However, if both of the following conditions are true

  • it takes more than 24 hours for the water to drain entirely from the hole
  • the site is flat

consider siting your rain garden at a different place in the yard and run a percolation test there. Percolation rates in different locations may vary.

If both conditions are still true after retesting in a different spot, then you may want to consider landscaping options for compacted soils or for a low wet area at this site instead.

If either condition is false
(preferred), then continue to Examine Slopes.

Rainscaping Guide Quick Links

What is Rainscaping?
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The Missouri Botanical Garden Rainscaping Guide is partially funded by the Mabel Dorn Reeder Foundation and US EPA Region 7 through the Missouri Department of Natural Resources (subgrant number G11-NPS-15), under Section 319 of the Clean Water Act.