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Pollinator Patch: Pollinator Rain Gardens

In April this year, I attended a "Lunch & Learn," hosted by the business improvement association in Waterloo, Ontario. One of the presentations at the workshop presented evidence from Environment Canada that rainstorms are intensifying in frequency and duration. Perhaps you’ve already experienced these episodes, as they generally lead to flash floods.

If you live in a city, you may have noticed that the nature of its paved infrastructure has eliminated some of the important ways that water naturally infiltrates into the ground without flooding. This is the reason that we need to look for solutions to mitigate those effects. The more canopies – think tall, full trees – and the more open natural ground we have in our cities, the less damage we will see due to flooding. However, there are also other ways to ameliorate the effects of such storms: installing rain gardens, cisterns, and permeable paving.

The least expensive option is to create a rain garden. Rain gardens reduce runoff and allow stormwater to soak slowly into the ground. The beauty of these shallow depressions or low-lying areas is that the plants in them also provide forage and habitat for pollinators and other fauna.

Your rain garden can be close to a downspout, but should be three or more metres away from your house. The species of shrubs, grasses, ferns and perennials that you choose should be able to tolerate both wet and dry conditions. You will want to choose native plants that are well adapted to your local conditions and bloom continuously from spring to fall. Lining your garden with stones or adding rock features will help prevent scouring and keep the drainage area porous.

One useful resource is the Canada Mortgage and Housing Corporation’s fabulous publication, Rain Gardens: Improve Stormwater Management in Your Yard. The document will guide you through calculations to determine the depth and size your rain garden should be, and includes plant lists, as well as other books and articles.

I will leave you with a list of the plants that local environmental biologist and native plant grower Jeff Thompson suggests, that are especially pollinator-friendly. I hope they can be a springboard for ideas for your rain garden! 

• Lance-leaf Coreopsis (Coreopsis lanceolata)

• Pink Milkweed (Asclepias incarnata)

• Pale Purple Coneflower (Echinacea pallida)

• Foxglove Beardtongue (Penstemon digitalis)

• Indian Grass (Sorgastrum nutans)

• Wild Bergamot (Monarda fistulosa)

• Black-eyed Susan (Rudbeckia hirta)

• Big bluestem grass (Andropogon gerardii)

• Little bluestem grass (Andropogon scoparius, synonym Schizachyrium scoparium)

• Blazing Star (Liatris spicata)

• Canada Anemone (Anemone canadensis)

• Stiff Goldenrod (Solidago rigida)

• Ohio Spiderwort (Tradescantia ohiensis)

• Hoary Vervain (Verbena stricta)

• Switch Grass (Panicum virgatum)

• Grey Headed Coneflower (Ratibida pinnata)

Some useful resources:

REEP Green Solutions http://www.reepwaterlooregion.ca/prog_rain_soak.php

Jeff Thompson, Native Plant Source http://www.nativeplantsource.com/

CHMC Rain Gardens document http://www.cmhc-schl.gc.ca/en/co/grho/grho_007.cfm

Picture above: A newly planted rain garden in Kitchener, Ontario.

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