Rain Gardens for the Home Landscape
By Lynda Ellis, Anoka County Extension Master Gardener
As we experience more droughts and dry spells, gardeners are looking for creative ways to conserve water while working with our natural landscape. One great way to do this is to create a rain garden. A rain garden captures rainfall that would otherwise flow down your lawn and driveway into streets and storm sewers and uses it to make your property more beautiful.
Rain gardens are not ponds, but they hold rainwater for short periods of time once appropriate plantings are established, which in turn attracts pollinators, birds, and other wildlife. By creating a natural filter for runoff, rain gardens divert water that could overburden local storm drains and treatment plants. If you are a handy homeowner, you can create one yourself, although assistance from a landscape professional may be helpful.
As in real estate, successful rain gardens are all about location, location, location. Your site needs to be in an area that temporarily floods, and it should be at least 10 feet from any buildings. Downspouts can often be diverted to direct water to a convenient place.
Once you have chosen a location, make sure the area will drain readily and is the appropriate size. To check for drainage, dig a wide hole six inches deep and fill it with water. If the water disappears within 24 hours, you have a suitable site. Ideally, your finished area will be between 100 to 300 square feet, and possibly more if you have a large hard surface area to deal with. A rain garden can handle the rain output from a hard surface three times its size.
Unless your site is already in a depression, you will need dig between four to ten inches below the surface of the soil to make a level ‘bowl.’ If your site isn’t level, you can use excavated soil to create a berm on the downslope side to prevent overflow, and you can experiment with a border.
Now comes the fun part – planting! Rain gardens have three distinct planting zones, and there are many native plants, trees and shrubs that can flourish in each of them.
The wet (deepest) zone: This area will hold water for the most amount of time. Blue flag iris (Iris versicolor) and great blue lobelia (Lobelia siphilitica) can handle getting their feet wet.
The mesic (middle) zone: This area can receive several inches of water but will not be flooded all the time. Try bottlebrush grass (Hystrix patula) for height.
The transitional zone (edges of the garden): This area will be the first to dry out. Try Anise hyssop (Agastache foeniculum) and Blazing star (Liatris spicata), especially in sunny locations.
Don’t forget to mulch; hardwood chips will not float away, and river rock can be used for the inlet point(s). You will still need to weed, especially the first year, and plan to water during dry spells.
With proper planning, you can create an enjoyable rain garden that makes the most of your topography and gives wildlife another reason to visit your yard.
Anoka County Master Gardeners are hosting guided garden tours in July and August: Three Seasons of Color; Growing Vegetables in the Home Garden; and Feeding the Community: Vegetable Donation Gardening. Tours are free and no registration is required. Visit anokamastergardeners.org for details.