Specially designed areas planted with native plants can provide natural places for rainwater to collect and soak into the ground. Rain from rooftop areas or paved areas can be diverted into these areas rather than into storm drains.
What is a rain garden?
It is a landscaped area with a depressed planting bed that receives rain water from impervious surfaces (roofs, roads, and parking lots).
What does a rain garden do?
A rain garden allows the rain water to pool for a short period of time in the garden. As the water soaks into the ground the water is cleaned by the plants and the soil microbes in the soil. This water now can recharge the ground water supply and release slowly into the stream.
Storm water that runs off impervious surfaces and into storm drains flows directly to our streams, carrying with it any pollutants it picked up along the way. The pollutants and the large volume of water rushing to the stream can have a dramatic impact on the stream’s habitat stability.
Can anyone make a rain garden?
It doesn’t take an engineering degree, just a shovel, some plants, and a few stones. It is easy and can be installed in a few short hours with a little planning.
What do you plant in a rain garden?
The plants need to be hearty and must be able to handle short periods of inundation after rain. Taller plants are preferable because of the pooling.
This is not a wetland and for most of the time soils will be well drained and dry. Look for plants preferring moist or well drained soils.
Step by step directions
Step 1: Choose the placement, shape, and impervious surface that will drain into the garden before you start digging. Garden size = ~20% of impervious surface it is draining.
Step 2: Make sure the garden depth is even throughout the bed. The garden should have gradually sloped sides.
Step 3: Uphill and downhill edges of the rain garden should be the same height. To do this, create a berm on the downhill side with soil or the sod dug out of the garden. Measure the height all across the down and uphill edges to ensure even height. This can be done with a sting line level and measuring tape. Stake string at the high point of the garden and measure across to different area of the berm.
Step 4: Soils should have high sand and low clay content. This increases the water retention capacity and increase drainage time. Soils can be amended. Compost should be added to help give plants a boost and enhance water retention.
Step 5: Tread inside the garden as little as possible to keep the soils airy and not compact. After planting make sure you water and mulch the garden thoroughly. Line the entrance of the garden with pebbles and stones to protect it from erosion.
IBM’s Rain Garden
View a video about IBM’s rain garden.