What is a Rain Garden?
A Rain Garden is kind of a misnomer for what it actually is. A Rain Garden is a lower area in landscaping where water loves to pool after a rainstorm and certain types of plants have been planted there. It could be in your yard, a public park or even a spot in a parking lot, anywhere rainwater collects.
Storm water runoff can be a big problem after heavy thunderstorms or just from our daily rain showers we have been getting the last couple of months. This water runs off of roofs, driveways, parking lots, streets and yards to eventually drain into the municipal storm drains. When this water comes off these surfaces, it is picking up such things as oil and gas, chemicals and fertilizers from yards and such along with other pollutants on the way to the drains and ditches. The EPA estimates 70% of the pollution in our streams, rivers and lakes is carried there by storm water.
To help reduce the excess water runoff, many towns and cities are encouraging businesses and homeowners to install rain gardens. They are specially constructed gardens located in lower areas of the landscaping where the rainwater can collect. The rain garden collects the water, filtering it and is slowly absorbed into the soil and the plants growing in the rain gardens, thus lowering the amount of runoff. When visiting the Bay Area in California, I noticed some of the parking lots drained to the center of the rows, collecting the water in the 3–4 foot grassy area. There were signs asking not to walk on the grass in these areas as they were for holding water.
Rain gardens don’t have to be very large, but you can make them any size you want as anything will help with filtering the water. You may not realize it, but a marsh is actually a huge rain garden. The plants in the marsh filter and clean the water along with the plants stabilizing the ground below the water.
To make a rain garden select an area in a lower part of your yard. If you have gutters, you could arrange to have them drain into this area. If you do not have gutters, then maybe you could funnel the rainwater to this area.
To plant your rain garden, check the soil first to see how long it holds water. It should not hold water but for a couple of days. If the soil is not a well-draining soil, you can amend it to be more porous. A good mix of sand (50%), topsoil (20-30%), and compost (20-30%) is a good start. Dig the area to loosen the existing soil and mix in the above mixture to a depth of about 2 feet before planting.
Choosing the right plants are key to making a rain garden successful. They need to be tolerant of sitting in water for a couple of days and then being able to withstand the dry times.
Selecting native plants and wildflowers are good choices as they are very adaptable. Many of the native plants usually have fewer disease and insect problems. Some of the plants that can be used are – ferns, iris, swamp milkweed, asters, black-eyed Susan along with Bluestar (Amsonia), Joe Pye weed, Coneflowers, Summersweet, Daylilies, Coral Bells, and Cardinal Flower. Some of the Hardy Hibiscus and Texas Star Hibiscus will do well planted in rain gardens also.
A couple of websites you can check out for more information on building a rain garden are: https://watersmart.tamu.edu/rain-garden/ and http://rainwaterharvesting.tamu.edu/files/2011/05/Rain-Garden-Plant-List-11-02-09.pdf
Sheri Bethard is part of Orange County Master Gardeners. For your horticultural questions, please call 409-882-7010, Tuesday and Thursdays from 10 a.m. to 2 p.m. or email email@example.com.