GreenUP’s top five things you might not have known about rain gardens

August 18th, 2022

Front yard rain garden with Swamp Milkweed, Great Blue Lobelia and Purple Coneflower blooms.

A rain garden boasting beautiful pollinator friendly plants like Swamp Milkweed, Great Blue Lobelia, and Purple Coneflower. (Photo by Hayley Goodchild, GreenUP Program Coordinator)

By Hayley Goodchild, NeighbourHOODS and Residential Programs Coordinator.

Read on to learn more about rain gardens and their beauty, practicality, and uniqueness.

Another column about rain gardening? You betcha! After all, what’s not to love about a garden that supports the health of the local watershed and wildlife, reduces flooding, and enhances the curb appeal of your home, school, or business

For those new to the concept, rain gardens are bowl-shaped gardens that take in stormwater runoff from nearby hard surfaces, such as a roof or an asphalt driveway. The plants and soil clean the rainwater by filtering out pollutants. Rain gardens come in many shapes, sizes, and styles, depending on the specifics of your space and your personal gardening style.

This week we’re sharing five things you may not know about rain gardens.

1. Rain gardens are often dry. Unlike a pond, which holds water throughout the year, rain gardens are designed to temporarily store water until it can be absorbed into the ground. Ideally, water in a rain garden will drain within 24 to 48 hours of a heavy rain event. During the summer, established rain gardens can go many weeks without water. The best part? Fewer mosquitoes in your garden!

2. An average residential rain garden in Peterborough can divert about 1.5 cubic metres of water from the storm sewer system each year. That’s roughly the same volume as 9.5 bathtubs. Keep in mind that bath water in Peterborough is treated before being returned to the Otonabee River, but roof runoff isn’t. Without treatment, runoff carries garbage and pollutants straight into the watershed.

By sending rainwater to a rain garden, you can harness the power of soil and plants to filter pollutants as water soaks into the ground. Imagine the potential for the watershed if more homeowners, schools, and businesses installed rain gardens on their properties. That’s a lot of bathtubs.

Rain gardens also help us adapt to the impacts of climate change, which include more precipitation in shorter amounts of time. They do this by reducing the amount of runoff the municipal stormwater system has to manage during heavy storms.

3. Rain gardens provide wonderful entertainment. As soon as you install one, you’ll fly out the door at the first hint of rain to watch the bowl fill and recede. Trust me!

Rainwater pools infront of residential home from two rain barrels.

Watching rainwater collect is half the fun of a newly planted rain garden. (Photo by Jenn McCallum)

4. You can incorporate trees into your rain garden if your space allows. It’s important to build your rain garden outside the canopy of any existing trees to protect their roots. However, there’s no reason why you can’t plant a new tree in your rain garden. Planting trees is critical for adapting to climate change, especially since extreme weather events can damage the urban tree canopy.

Some of our favourites include River Birch (Betula nigra), Hackberry (Celtis occidentalis), Eastern White Cedar (Thuja occidentalis), and Serviceberry (Amelanchier spp.). These native trees and large shrubs are well-suited to the variable moisture conditions found in rain gardens and add height and year-round interest. You can customize your rain garden with many native plants and trees so it becomes uniquely yours.

This River Birch is thriving in a rain garden at Jimaan’ndewemgadnong Pocket Park in downtown Nogojiwanong/Peterborough.

This River Birch is thriving in a rain garden at Jimaan’ndewemgadnong Pocket Park in downtown Nogojiwanong/Peterborough. (Photo by Geneviève Ramage)

5. Eligible homeowners can receive up to $1000 from the City of Peterborough to install a rain garden at home.

That’s wild!

In addition to the subsidy, you get to enjoy all the secondary benefits that rain gardens offer, such as butterfly visits and the envy of your neighbours. Plus, GreenUP is partnering with the City of Peterborough to provide applicants with consultation visits and customized advice.

The application process begins with an eligibility assessment. Once you’re pre-approved, you will receive resources and support to design your own unique garden. Additionally, applicants can take advantage of up to two site visits by GreenUP staff during the design and installation process. One of these visits is required, and must take place during construction. The other visit can be used at a time of the applicant’s choosing, for additional advice on garden design, application support, maintenance or plant selection.

The subsidy covers the costs of plants, soil, mulch, rock, and other non-equipment expenses incurred while building a rain garden. The subsidy can also be used to hire a landscape contractor for design and/or construction, if desired.

Infographic about Nature-Based Climate Solutions, which includes rain gardens as an enhanced asset.

Rain gardens are one type of ‘green infrastructure’ that will help cities mitigate and adapt to climate change. (Photo by Green Infrastructure Ontario Coalition)

It’s not too late to reap the benefits of a rain garden and receive a subsidy this year. For more information about the Rain Garden Subsidy program, visit www.peterborough.ca/raingarden, or direct questions to Hayley Goodchild at hayley.goodchild@greenup.on.ca or by phone at (705) 748-3238 ext. 213.

GreenUP can help you source plants suitable for your rain garden. Visit the Ecology Park and speak to our staff in the Native Plant & Tree Nursery during our hours of operation, Thursdays 10am to 6pm, and Fridays, Saturdays, and Sundays from 10am to 4pm.

Posted in gardening, rain garden, water


City of Peterborough

City of Peterborough

The City of Peterborough supports GreenUP through an annual Community Service Grant. This funding supports many of our programs and services which positively impact Peterborough residents each day....

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