A rain garden is a shallow, constructed depression to catch rainwater. It contains plants that tolerate standing water for several hours. If it is designed properly, all water from a rain event will soak into the ground within 48-72 hours.  Rain gardens receive a rush of polluted stormwater from hard surfaces (such as sidewalks, driveways, roofs, and streets), hold the water for a short period of time, and allow it to naturally soak into the ground.  The plants and soil remove most pollutants so that the rainwater can recharge the groundwater with clean healthy water. 

Image Credit: Tip of the Mitt Watershed Council

What are the benefits?

Rain gardens increase the amount of water that filters into the ground, removing pollutants and recharging groundwater. This helps protect lakes and rivers by intercepting urban stormwater that would have run off hard surfaces and picked up pollutants along the way. These pollutants include lawn fertilizers, leaves and grass, sediment, pesticides, oil and other automotive fluids, and bacteria from pet and wildlife waste. Rain gardens also enhance the beauty of yards and neighborhoods and provide valuable habitat for birds, butterflies and many beneficial insects.

Rain Garden plants

Rain gardens usually are filled with native plants. Native plants are evolved to fit their environment. They are naturally drought, flood and pest resistant in their native region. That translates to less work for the novice gardener and the pro, once all the initial work is done.

Warren SWCD Rain Garden Plant Guide

CORGI Native Plants for Rain Gardens

additional Resources

Raingarden Guide for Southwest Ohio:  An OSUE, Hamilton County, publication developed through funding support from the Metropolitan Sewer District of Greater Cincinnati.  This manual is a practical handbook for home gardeners!

Rain Garden Manual:  A wonderful resource pdf created for Ohioians by ​Geauga Soil and Water Conservation District and the Ohio Department of Natural Resources - Division of Wildlife.

Central Ohio Raingarden Initiative:  ​The Central Ohio Rain Garden Initiative (CORGI) is a collaborative effort to promote the benefits of rain gardens for community beautification and clean water.  This website is funded by a grant from the Ohio Environmental Protection Agency’s Ohio Environmental Education Fund.

Blue Thumb! Planting for Clean Water:  This design and installation guide is a valuable raingarden reference guide for homeowners and professional designers. Thoroughly researched and beautifully illustrated, the book is approachable for beginners, yet contains detailed information for landscape professionals. It contains easy-to-follow instructions on designing, installing, planting and caring for raingardens, including example plans for different settings and information on more than 100 suitable plants from Zones 3, 4, and 5 in the Midwest.

Steps to creating a rain Garden

1.  Assess your site

• Take a look at your property and find out from where your source of water will be coming (a downspout, driveway, patio, or sidewalk).
• Your rain garden should be close to this source of runoff, but at least 10-20 feet from the foundation of your home.
• Be conscious of any trees on your site – we don’t want to disturb an already established root system.
• Call OUPS before you dig – (800)362-2764 – to avoid underground utilities.
• Consider an overflow – perhaps you will direct any overflow back into the downspout that is connected to the street.
• Also consider your mowing habits and how wide your mower is, especially if you usually hire someone to do the work. Be sure there is enough room for a mower to pass through whatever other landscaping is already in place next to your garden.

2.  Know your soils

• The purpose of a rain garden is to move excess rain water into the soil (infiltrate) rather than allowing it to runoff your property. A rain garden will not function properly if the surface infiltration rate is less than 0.5" to 1" per hour. Many areas in the Greater Cincinnati area have heavy clay soils and water moves very slowly into these soils. Also, water infiltrates slowly into soils that have been compacted by construction or other activities.
• Click HERE for the 5 steps to determine your infiltration rate.

​3.  Sizing

• Consult one of the resources on this page for sizing formulas.

4.  Get ready to dig!

• In order to start digging, outline the shape of your garden with marking spray, flags, or a garden hose.
• Remove the existing top layer of sod, and dig down to the rain garden depth.
• Till up the top couple inches of soil.
• Amend soil if necessary.
• Grade the bottom of the garden evenly.

5.  Plants

• Choosing your plants is just as important as sizing your garden correctly. They will be doing most of the work in your garden.
• Choose plants that are tolerant of flooding and also tolerant of drought (since it won’t be raining everyday, and your garden should drain in 24-48 hours).
• Consider color, bloom time, and height of the plants. A wide variety of colors and bloom time are available.
• Also consider using native plants, as they are better suited to our soils, climate, and pollinators. Cultivars of natives also work well, as they may prove to be less aggressive and more compact.
• Locate the plants in the garden according to their tolerance of water – the most water tolerant plants should be placed closest to where the water will enter the rain garden.
• After the plants have been planted, add a 2-3” layer of pine needle mulch or double shredded hardwood mulch to keep in moisture and keep out weeds.

6.  Water/Maintain

• Your rain garden will need to be watered throughout the first growing season. If you use native plants, they should take off and do well on their own after their first year.
• The plants will fill in as the years go by, but applying mulch year after year is a good idea. Over time, less mulch will be required.
• Watch for gullies and erosion – a quick fix to an unanticipated path of water entering the garden is to place several cobble stones at that entry point to slow and spread the water.
• In the fall and spring, be sure to clear out any leaves that may have collected at the water entry point to your garden to be sure the flow of water is not restricted.
• Labeling your plants is a good idea, especially if you aren’t sure which ones are weeds when they come back in the spring or if you have friends or co-workers over to see your garden!

The Story of a Rain Garden

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