Rain Gardens

Rain Gardens are a great idea for many reasons. Why not add one to your home garden?

As our climate changes, WATER is increasingly important as a resource. The reduction of worldwide annual rainfall has prompted partial or even complete bans on watering. A regular supply of rain water is not always available when gardeners need it. More often now, we alternate between huge downpours, and more frequent and longer periods of drought. When the big deluges hit parched ground, we deal with overflowing storm drains, flooded basements, and additional pollution of streams, rivers and lakes. This flood/drought trend is predicted to continue in the foreseeable future.

We gardeners need to consider this reality when planning our gardens by making the best possible use of available rain water and choosing our landscaping and planting options carefully. There are a number of things we can do. Here’s a quick summary of a few:

  • Use more permeable pavers or ground covers in our landscape rather than solid surfaces.
  • Choose and grow plants that have the ability to survive with less water.
  • Feed and amend our soil so it’s rich in organic materials and retains as much moisture as possible.
  • Direct rain water into rain gardens, barrels and onto lawns and gardens rather than into storm sewers.
    • See the Ontario Horticultural Association’s newly published booklet Roll Out the Barrel 
    • or ..Create a Rain Garden – Let’s focus a bit more on this idea

Creating a Rain Garden

A rain garden is designed to keep the water where we need it, in our gardens, by capturing rainwater from a roof, driveway, and any other hard surfaces and directing it to a location in our yards where it can soak in. Basically a rain garden started with creating a depression in the yard, filling it with good soil, then adding plants that can handle both dry and wet periods.

Some Basics for Creating a Rain Garden:

1. Choose a site by first seeing where rainwater from the roof typically flows. Ensure your chosen site is lower if possible and at least ten feet away from the house foundation to prevent basement moisture.

2. Dig a depression. A depth of four inches is sufficient, however 8-12 inches is even better as it will allow you to add organic matter and mulch to increase water retention of your soil. If your property is sloped, use the removed soil to build a berm.

3. Add a shallow channel from your downspout, lay filter cloth, then cover it with river rock which looks great and prevents erosion.

4. Choose plants that tolerate both wet feet and dry periods. Native plants are ideal for this garden as are shrubs and small trees. Here are a few of the native plants that like rain water and can stand a drought. Many more are listed in the resources linked below.

  • Swamp milkweed for the butterflies
    Red Osier dogwood
    Joe Pye Weed
    Bee balm
    Royal fern
    Goatsbeard
    River Birch
    Cardinal Flower
    Blue lobelia

5. Place plants close together and Mulch well to limit evaporation of moisture from the soil and discourage weeds.

Properties of a Rain Garden:

  • Uses rainfall for your plants rather than letting it run off the property.
  • Deeply rooted plants will help reduce erosion on a sloping property.
  • Acts as a filter for pollutants – fertilizers, herbicides and road salt.
  • Helps reduce impact on storm water management systems; keeping local waterways cleaner.
  • Provides moisture that supports life of all kinds – including butterflies, birds and pollinators. A rain garden also doesn’t offer a breeding site for mosquitoes.
  • A rain garden is lower maintenance than lawn and it helps reduce our water bills.

Rain Gardens work. 

Here are more great resources to help you with yours:

Rain Garden Design Templates – Low Impact Development Centre

City of London – Gardens Don’t Have to be Thirsty

University of Minnesota – Zone 5 Rain Garden Plants

Penn State extension – Plants for eco-friendly rain gardens

Essex Conservation authority – Guide to creating a Rain Garden

compiled by Linda Armstrong, London Middlesex Master Gardeners