Rain garden project

Sustainable Building Demonstration Project

Rain Gardens

In 2005, Leonardo Academy staff installed rain gardens in the front and back yard of Leonardo Academy's office building as part of our Sustainable House Demonstration Project. Read on to find more about rain gardens, what services the gardens provide, and the step-by-step process we used to install the gardens.

What is a rain garden?

Rain gardens are landscaped plantings of native wildflowers and grasses that soak up rain water runoff from impervious surfaces, those surfaces such as roofs and driveways that do not absorb much water. The native prairie plants used in rain gardens have extensive root systems – up to 15 feet deep – that allow water to slowly soak into the ground. Rain gardens collect rainwater that would otherwise become runoff, thereby reducing the amount of water and pollutants that enter local storm drains and eventually empty into nearby streams and lakes.

Rain gardens make beautiful additions to a front or backyard. A rain garden allows 30 percent more water to soak into the ground than a patch of conventional lawn! The colorful wildflowers create a gorgeous display of blooms throughout the summer and fall and attract a lot of interesting insects including butterflies, moths, and bumblebees.

Another great reason to plant a rain garden is that they are very low maintenance after the first years of installation. These native plantings do not require mowing, fertilizers, or watering – except in extreme droughts. So add a rain garden to your property and watch as it transforms into an array of color while helping protect your local environment!

What were the goals of our rain garden installation?

minimize water and fertilizer inputs to the yard
collect stormwater runoff from nearby impervious surfaces - our project site is located in the downtown isthmus area of Madison where protecting water quality is very important
reduce local flooding during extreme rain events
demonstrate sustainable alternatives to turf grass landscaping
educate the surrounding community about rain gardens
create a beautiful addition to the lawn
provide food and habitat for insects and birds

Our recommended step-by-step installation process

Step 1: Investigate funding sources for rain garden installation

Our rain garden installation was funded by a $500 grant from the Graham-Martin Prairie Foundation’s Plant Dane! 2005 Native Plant and Seed Grant Program. This particular grant program will provide up to $10,000 for municipalities, schools and nonprofit organizations and up to $200 for homeowners to install a rain garden. In order to receive a grant, the recipient must attend a Dane County-sponsored educational workshop on establishing the gardens and plants. Other funding opportunities are available and it is worthwhile to do some investigating.

Step 2: Choose the desired rain garden location.

Rain gardens are strategically located to receive runoff – often in low areas, where roof downspouts empty, or where water can be channeled from a large impervious area such as a driveway. Observe where your rain goes or pools during the next rain event to determine the best location on your property.

Most prairie wildflowers and grasses likely sunny locations, so choose a spot that is not shaded the entire day.

We placed the backyard rain garden in a location that receives runoff from a nearby alley and a driveway. The front yard rain garden is located where the ground gently slopes downward and collects rain from the roof and the lawn, decreasing the amount of water that runs off onto the sidewalk and into the storm sewer.

Step 3: Choose native plants based upon site characteristics and your interests

Select wildflowers and grasses that were historically found in your region of the state. These species are often better adapted to your particular climate and can be hardier than species that arre not originally from your area. For ideas on which plants are appropriate, talk with local nurseries that sell native species or browse online.

Decide whether you will plant plugs - small seedlings - or if you will use seed. This decision will depend upon the money, time, and maintenance that you would like to invest into your rain garden. Planting plugs is more costly, but requires less weeding and can results in a beautiful planting within a year. Planting seeds may require up to three years of maintenance, but is lower in cost and may result in a more diverse, and surprising, planting. And, of course, choose plants that you think will look nice.

We used prairie plugs in our plantings and the garden was beautiful the following year!

Step 4: Stake the proposed rain garden site

It is helpful to use a piece of string to form the garden shape. A crescent shape works well, with the indented portion facing the runoff source. Decide on an appropriate size based upon your property and amount of runoff.

We created two crescent shaped rain gardens. Because the backyard receives more direct runoff, we made this rain garden a little larger (110 square feet) than the garden in the front yard (81 square feet).

Step 5: Rototill or work up the existing turf.

It is important to start with a fresh surface for your rain garden planting. Remove any existing turf grass, weeds, and roots. Working the soil to 3 inches deep should be sufficient.

Step 6: Prepare the soil.

Additional soil may need to be added to your ground, especially if the soil on your property is lacking some nutrients or is of low vitality. We conducted a soil test on our soil to determine whether soil nutrients and pH were in balance (it is often the case that city lawns are already high in phosphorus and nitrogen). You may also want to alter the slope of the area to improve drainage or create berms to stabilize the planting.

We added some store bought soil to the top of the area we worked up and also created berms along the back of the gardens (along the long side of the crescent) by building up soil and adding mulch. The berms provide extra stabilization so that soil is not swept away during strong rain events during the initial years of the planting.

We created a trench that funnels water directly from the alley and the roof downspout to the backyard rain garden.

Step 7: Plant away! Add water and mulch.

Choose the appropriate time of year to seed or plant your prairie plugs based on your region.

We planted our prairie plugs before the end of September. The gardens were watered immediately following planting. We mulched the garden with wood chips to decrease the amount of weed growth and water loss.

Step 8: Maintain the rain garden.

You will have to invest some time into your garden during the first season to ensure its success. We recommend giving the garden about an inch of water each week until the plants are well established. Weed the garden to keep out undesirable vegetation that will compete with your plants for light and water. Replenish mulch as needed.

Back to Projects