How to Create a Rain Garden
A rain garden filled with wildflowers and native plants adds more than beauty to your home. It's an attractive and environmentally-friendly way to catch stormwater that runs off roofs, driveways and other surfaces. A rain garden also creates a welcome habitat for birds, butterflies and other creatures. Get steps on how to create a rain garden and planting ideas below.
When you create a rain garden, which is a shallow, planted depression, it collects water that slowly soaks into the soil. Rain gardens help prevent flooding and soil erosion. As the water collects in the rain garden, it slowly soaks into the soil. This also helps filter out pollutants like pesticides and oil from streets, so they don’t end up in waterways.
The first step in making a rain garden is choosing your location. If you plan to collect rain from your driveway, your location should be where you get the most runoff. If you plan to use rain from your roof, your spot should be closer to your home. These steps will help you pick the right location:
- Keep your rain garden away from your septic system or underground utility lines. Call 811 before you dig if you don't know where the utility lines are.
- Keep the rain garden at least 10 to 15 feet away from your house so water won’t seep into the foundation.
- Avoid putting the garden under a tree or digging where you might damage tree and shrub roots.
- Put the rain garden in an area that gets at least six hours of sun.
- Position the rain garden so it can collect the stormwater before it flows into streets and sewer drains.
If you have a steep incline of 15 percent or more, do not choose that slope for your location. The excess water can trigger a landslide.
Tip: Before you start, get any required permissions from your local zoning board. Check that your neighborhood doesn't have any restrictions.
Test Soil & Prep
Test your soil before you dig out your rain garden hole. Rain gardens aren't recommended for all types of soils. You'll want to know how fast the water will drain. Do the test the day after a rain, when the soil is saturated, in the spot where you want the garden. Follow these steps to do your test:
- Use a measuring tape to measure out six inches in diameter and six inches deep.
- Use a shovel to dig a hole.
- Fill the hole with water.
- Let it drain and refill it.
- Wait 24 hours to see if the water is gone.
If the water is gone, the site is probably good for a rain garden. If it isn't gone, test another part of your yard or consider making a pond.
The kind of soil you have will help determine the size of your rain garden. Water is absorbed fastest in sandy soils and slowest in clay-like soils. If necessary, you may want to amend the soil in your planting area with sand and mulch. You'll probably need a large rain garden if your soil is mostly clay.
Mark your rain garden location with ground paint or string tied to stakes. Mark where the stormwater flows from your house or driveway toward the garden. This is your rain garden inlet. If you don’t have a natural inlet, you can create one by aiming your downspouts toward the garden site. Use downspout extensions or dig a shallow trench filled with rocks or gravel to direct the water to the garden.
Mark your overflow area on the downhill side of your garden. The overflow area should direct the overflow water from your rain garden toward the lawn or a secondary garden. This will ensure that during prolonged periods or excess rainfall, the water will flow out through the overflow path, rather than spill over on all sides.
Dig Rain Garden, Inlet & Overflow Area
Remove grass and weeds from the rain garden, overflow and inlet site. Use a hoe to clear away the top layer of vegetation. If the vegetation is very thick, cover it with black plastic sheeting for a few days and let heat from the sun kill it.
The soil in a rain garden shouldn’t be compacted so try to work from the edge of the rain garden as much as you can, rather than the center. Angle the sides of the hole so they slope slightly toward the center. Lay out a tarp to collect the soil you remove. You will need about 25 percent to fill the bed back up.
Rain gardens require a special mix of soil to work properly. The bulk of the soil is made up of compost and sand to encourage proper drainage. Evenly mix together 25 percent compost, 25 percent soil and 50 percent sand before filling in the hole. As you fill the hole, lightly pat the area down with your feet every 6 to 7 inches. Continue filling and patting down the soil until you have added 21 to 24 inches of soil. This will leave 10 to 12 inches for plants, mulch and water.
Place a few small rocks, about as big as a fist and smaller, at the entrance and exit of the garden to keep soil from eroding at the inlet and overflow sites. Place decorative rocks up the inlet trench if you need to build one. The key is to limit erosion at these sites and the edges of the garden.
Now it’s time to plant your rain garden.
- Start by positioning your plants in the garden bed while they're still in their containers. Move them around until you have the look you want. Read the tags and follow the recommended spacing. Consider how big each plant will be when it’s full grown.
- Remove the plants from their containers. Put your hand on top of the container, touching the soil. Turn the plant upside down. Tap the bottom until you feel the plant start to slide out. Don’t pull the plant out by its stem or top growth. It can harm the plant.
- Gently loosen the root ball with your fingers. It’s okay if a few of the roots break. Plant the plants in the rain garden bed. Don’t plant them deeper than the size of the container they came out of. Pat down the soil around the plant and water well.
- Cover the rain garden bed with at least 2 1/2 inches but not more than 4 inches of mulch. This will protect the bed against drought, limit weeds and give the bed a tidy look. It also helps the bed absorb and filter the rainwater and runoff.
- Water your plants every few days for the first four weeks. If the season is particularly dry, continue to give them an inch of water every week for the first year or until the plants are established.
- Because the soil is rich with compost, you do not need to fertilize your rain garden.
Rain Garden Plant Ideas
For best results in your rain garden, grow a mix of plants including wildflowers, natives and other low-maintenance plants. This makes the garden visually appealing. It also creates different levels of root growth, which can more efficiently absorb the water. Some plants reach deep with their roots, drawing the water from the bottom. Others are shallow feeders, meaning they take water from the top layers.
Start with plants not seeds. Seeds can wash away with the stormwater before they have time to sprout. Select plants that tolerate periods when there’s no water in the rain garden and periods of excess water.
Try a combination of these plants suited for rain gardens:
- Little bluestem is a full-sun plant that turns red/brown in the fall. It reaches 3 to 5 feet in height.
- Big bluestem is a partial sun and full sun plant that turns burgundy in the fall. It can reach up to 8 feet in height.
- Switchgrass is a sun-loving, moisture loving plant. It has brilliant fall colors and looks great in winter. It grows to around 5 feet tall.
- Japanese forest grass is a shade-loving, moisture-loving plant that grows to a height of 1 to 1 1/2 feet. It comes in green and gold and green and white varieties.
- Flag irises can tolerate moist and drought conditions, making them well-suited to the edges of a rain garden. They prefer full sun and can grow up to 20 inches tall.
- New England aster is a moisture-loving plant that enjoys full and partial sun. It can grow up to 6 feet tall. It’s a favorite among pollinators.
- Black-eyed Susans are deer-resistant flowers that enjoy sun and partial sun areas. They bloom from June to August. Black-eyed Susans grow up to 3 feet tall.
- White turtlehead thrives in moist conditions and enjoys sun and shade alike. It grows between 3 and 5 feet tall. It attracts butterflies and hummingbirds.
- Rose mallow is a moisture-loving, shrub-like plant that enjoys full sun exposure. It produces showy flowers from mid-summer to autumn. It can grow up to 7 feet tall with a 4 foot spread. Give the plants room for proper airflow by planting them 36 inches apart.
- Eastern ninebark enjoys sun and partial sun and can grow up to 10 feet tall. It can tolerate wet and dry conditions.
- Nannyberry viburnum is a moisture-loving plant that enjoys full sun and shade. It can grow up to 30 feet tall.
- Common elderberry shrub is a moisture-loving, tree-like plant that tolerates sun and partial sun. It can grow up to 12 feet tall.
Care & Maintenance Tips
Rain gardens are typically low maintenance, but there are a few things to monitor along the way:
- Watch for areas of erosion, especially at the inlet and outflow areas. Keep the areas clear of debris and add more decorative rocks as needed.
- Replace dead plants quickly.
- Weed regularly.
- Check the mulch depth yearly. Add more to any areas that have less than 2 1/2 inches of mulch.
Tip: As the plants grow and fill in, they’ll crowd out the weeds and the rain garden will be easier to maintain.
Rain gardens make the areas near storm drains look better. They also prevent flooding and create habitat for birds, butterflies and other beneficial creatures. Get the soil, tools and plants you need to start your raind garden. Use The Home Depot Mobile App to locate products and check inventory. We’ll take you to the exact aisle and bay.
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