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Rain Gardens

Sometimes it rains. When it rains hard and fast, the ground and the storm sewers cannot handle all the water and there is flooding. Rain gardens help absorb some of that water. A rain garden is a special garden that collects the rain and filters, or cleans the water before it makes its way through the ground and sewers into our streams, rivers, lakes and eventually oceans. Rain gardens are being planted in cities that have covered the ground with roads, parking lots, and buildings. Roads, parking lots and buildings are impervious surfaces that cannot absorb water. Rainfall needs to be absorbed by permeable ground, or ground that can pass water into underground aquifers. Aquifers are the earth’s stores of underground water. Rain gardens reduce storm water pollutants, help prevent flooding, and improve water quality. Rain gardens also create special wildlife habitats for birds, butterflies, and insects. Rain gardens are beautiful and useful!

Let it rain!

Activity 1 Place Your Rain Garden

Next time it rains, watch to see what happens. Where does the water go? Where does it collect, where does it soak in and where does it run? Watching what happens when it rains will help you locate your rain garden. Where the water collects means that the soil is not too permeable and cannot be absorbed. Where the water runs off means that the surface is impervious. Where the water soaks in produces the right conditions to build a rain garden. After watching the rain, take a picture of your house. Draw a line on the ground around your house. Using the door as a measure (most doors are 7’ high) measure 10 feet away from the house and 30’ away from the downspouts of the house. Select the area where you noticed the water being absorbed and you can begin to plan your rain garden. Select a partially sunny spot some distance from any tree roots. After calling the utility company in your city to make sure that your garden area does not contain underground utilities, it is time to test your soil.

Activity 2 Prepare Your Rain Garden

After locating where you would like to place your rain garden, it is time to test the soil. The easiest way to test the soil is to dig a hole 1 foot by 1 foot by 1 foot. Pour a bucket of water into your hole and if the water drains at least 1" per hour, you can build a rain garden! If it drains more slowly, find a new place for your garden. Next, take a small handful of soil, add a few drops of water and roll it into a ball. Then flatten the ball. If the soil stays together and does not break into 1” or less pieces, the soil may have too much clay to be a good rain garden. If there is too much clay, you should dig 2-3 feet down and fill the depression with 12” of pea gravel topped with 6“ of sand and then 6” of topsoil. Measuring the width and height and depth of the layers will help you estimate how much new material you will need. Finally, smooth the top layer inward so your rain garden will catch and hold water. Now you are off to read about rain garden plants!

Activity 3 Plant Your Rain Garden

Once your rain garden has its new layers of permeable soil, it is time to select plants and plant them! Using the resources on page c or by calling a local gardener, you will find many local plants that will grow happily in your rain garden. Dogwood shrubs, ferns, grasses, wild geraniums, day lilies, and other flowering perennials will grow with little or no maintenance after planting. Select your plants for your growing season and region, availability, sunlight needs, and height, color, shape and size. Be sure to keep them moist during the first growing season.

Activity 4 Keep A Gardening Journal

Using Google Earth, find an aerial view of your community. Look at the rooftops, streets, roads, and parking lots. See if you can find the stream, river, pond or water collecting area. You can compute all of the non-pervious area of your community and compare it with the permeable area that can filter water. You can also check to see if your community has problems with flooding, or if the waterways are polluted. You can then suggest areas in your community that might be good places for rain gardens. Schoolyards, parks, and boulevard medians are good places to start. Perhaps your community will start an incentive for homeowners to plant rain gardens in their yards.

Become a rain garden activist!

Review

  1. A rain garden only catches rain.

  2. Recharging the underground aquifers comes mostly from:

  3. Rain gardens help filter storm water and improve local water quality.

  4. Rain gardens should be placed in the yard where the water ponds.

  5. When designing a rain garden, it is important to:

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