Photo courtesy of Mr Clambake at Flickr.com.
During a rainstorm, several inches of water can pour down over a short period of time. Heavy rainfall can tear plants out by their roots and rapidly erode soil. Even light rainfall can wash away nutrients and fertilizer off of the ground. Runoff often collects in streams and ponds, where it can cause algae blooms that kill fish and wildlife.
One way to protect your landscape and the local environment from storm runoff is to build a rain garden. A rain garden is a collection of deep rooted plants placed in such a way that they filter runoff and help the ground absorb moisture. Native plants work very well in rain gardens, as do many flowers and vegetables that offer habitat for native animal species.
To build a rain garden, start by grabbing a shovel. Rain gardens should be set slightly below the surrounding ground level so that rainwater is funneled into them. You can dig a bowl shaped depression, or a trench that leads downhill from your your rain gutters. If the surrounding soil is clay and doesn’t drain well, you may need to bury drainage pipes at the bottom of the holes that will direct excess water into the sewer system.
The second step is to fill the hole or trench with spongy soil that will absorb lots of water. Mulched cedar chips work well, as does compost, vermiculite, or coir. After you fill the holes in the ground and allow the dirt to settle, the rain garden should still be 2-4 inches lower than the surrounding area.
Test the drainage of the soil by wetting it. Good drainage is important because standing water can attract mosquitoes. If the soil drains within 48 hours, mosquitoes wont be a problem. 2 days is the minimum time that mosquitoes need to complete their breeding cycle. If it rains for several days and the rain garden stays wet, then you may want to treat the water with organic mosquito controls.
Third, plant a variety of native bushes, plants, and flowers in your rain garden. Their deep roots will keep the soil from washing away, and they’ll also draw water down into the water table. Native plants are hardy, and many of them will help neutralize pollutants and excess nutrients from the flood water. If you have heavy rainfall in your area, you should choose moisture tolerant plants with broad leaves that will help the water transpire quickly. If you live in a warmer climate with infrequent rains, well, hardy cactus and shrubs have evolved to handle flash floods!
Here are some other plants that do well in rainwater gardens:
Mosquito Fern (Azolla palmatum)
Bulblet Fern (Cystopteris bulbifera)
Log Fern (Dryopteris goldiana)
Clinton’s Wood Fern (Dryoperis clintonia)
Sensitive Fern (Onoclea sensibilis)
Royal Fern (Osmunda regalis)
Cinnamon Fern (Osmunda cinnemomea)
Marsh Fern (Thelypteris palustra)
Photo courtesy of Sandie’s Pal’s at Flickr.com.
