Rain Gardens

What is a Raingarden? 

Raingardens are where form meets function and gutter meets the ground.
They are gardens designed to soak up rain, mainly from roofs, but also from driveway and patios. Raingardens look like regular flower gardens, but they are so much more. When it rains, a raingarden fills with a few inches of water and allows water to slowly filter into the ground rather than running off to storm drains that connect to surface water (streams and bays) and groundwater (drinking water source). Compared to a same size patch of lawn, raingardens allow about 75% more water to soak into the ground! They also provide wildlife habitat and add beauty to neighborhoods!

Plan: Choosing a spot
Raingardens can be designed to catch water from a roof or driveway. Pick a hilly spot with a slight depression; you’ll have less digging to do.

  • Are not a solution to constant wet areas!
  • Must have good drainage so that the water can soak in within 24 hours after a rainfall. This will detract mosquitoes.
  • Should be at least 10 feet away from a building to prevent seepage into the building. Use a gutter lead or build a swale to direct rainwater from roof or driveway to raingarden.
  • Should not be built over a septic system.
  • Must include an overflow outlet to transport excess rain to a proper location (not your neighbor’s lawn!).

Prepare: How Big?
Size of raingarden will depend upon 3 key factors:

  1. Size of drainage area
  2. Type of soils on site
  3. Depth of raingarden

A typical residential raingarden is about 50-100 square feet. For advice on calculating dimensions of raingarden, contact the Nassau County Soil and Water Conservation District at 516-364-5860 or email at Nassauswcd@optonline.net.


Plant: Ready to Dig?

  • Before digging, call Dig Safe NY at 1-800-272-4480 to detect underground utility lines!
  • Use string to outline shape of raingarden.
  • More digging will be required on uphill side.
  • Use an extra soil to build a berm on downhill side, so soil will be carted away.
  • Bottom of raingarden must be flat and level.
  • Make an overflow outlet for heavy rain events.

Plant Selection
Choose plants that:

  • Have a variety of heights, textures, and bloom times.
  • Native perennial plants are the best. It is critical to select “dry” plants that can tolerate infrequent heavy “wet” conditions like a major storm, and that are suited to sun or shade exposure of raingarden.

Tip: Dig each hole twice the width of plant root-ball. The hole should be deep enough so that top of plant’s root-ball is level with ground.​​​​​​​

M-F: 9am - 3:30pm



Nassau Hall
1864 Muttontown Road
Syosset, NY 11791

Nassau County Soil and Water Conservation District