Rain gardens catch the rain from a disconnected downspout so it drains into the soil slowly. This keeps storm water pollution out of our storm drains, rivers and streams, and creates a beautiful garden feature in your yard. Planted with native plants, rain gardens also attract beautiful birds, bees and butterflies and thrive without chemical fertilizers or pesticides. Metro Natural Gardening Specialist, Carl Grimm, showed us how simple it can be to make a rain garden.
What is a rain garden?
• It’s a sunken garden bed that catches and filters runoff from roofs, driveways or other hard surfaces. It keeps polluted water out of our storm-water system, instead helping clean it and replenish our groundwater supplies.
• Planted with beautiful native plants, it adds habitat for birds, bees, butterflies and other beneficial insects, and thrives without chemical fertilizers or pesticides.
• Rain gardens help make rivers and streams healthier for you and for fish.
What are the essentials of building a rain garden?
• Plan carefully. You’ll need a site that’s not too steep, that drains well, and that does not slope into your foundation or your neighbor’s property. You’ll also need to calculate the size of the garden to make sure it can handle the amount of water draining into it. Not every site is suitable. Consult your city, county or storm water utility to be sure.
• Dig, plant and mulch. Once you have a plan checked out by your local jurisdiction, you can get to work digging the sunken area and mounding up the edges. Work some compost into the soil, plant your native plants and spread some mulch. The plants and mulch help filter pollutants from the water. A stone or splash block at the downspout outflow helps prevent erosion.
• Disconnect your downspout . Be sure your downspout outflow is 2 to 3 feet from the foundation (or 5 feet if you have a basement), and cap the drain it went into.
• Monitor and maintain. Always check to see that your rain garden is draining well – it should not be full for more than two days. Typically after a few years you’ll need to thin out the plants, and amend and mulch the soil.
Rain gardens can be fairly tricky to design and install. Seek the help of an expert.
• Contact your city, county, soil and water conservation district, or storm water utility first; many offer free site visits, financial incentives, plans and other resources. We’ll put links to local agencies on KATU.com.
Get a free copy of the Oregon Rain Garden Guide by calling us at Metro at 234-3000.
For local approvals and resources, contact your city, county or storm water utility.
• Washington County Clean Water Services
• East Multnomah Soil and Water Conservation District:
• West Multnomah Soil and Water Conservation District:
• Clackamas Soil and Water Conservation District:
• City of Portland:
• Oregon Tilth Organic Land Care practitioners