What is a Raingarden?

Image of a Raingarden

A raingarden, as seen above, is a shallow depression that is designed to capture rainwater and allow it to soak into the ground within a 24-48 hour period.  Most gardens are best designed with plants that are well adapted to the unique conditions of the garden and your region (such as local native plants or cultivars of those same plants).    

What is a raingarden?

A raingarden is a bowl-shaped garden that captures and holds rainwater runoff, allowing it to soak into the soil and filter naturally through the ground.  Raingardens help to reduce the amount of rainwater runoff that would otherwise carry pollutants from our yards, houses, driveways, and streets directly to our lakes and rivers through the storm sewer system. By capturing this polluted water and allowing it to filter naturally through the soil, it reaches our local water bodies clean and cool.  Raingardens are also a way to beautify your property.  Using perennial plants that require little maintenance and thrive without fertilizer or pesticides, we enhance the value and attractiveness of our neighborhood and community.

What causes rainwater pollution?

Catchbasin Road Gunk

Rainwater pollution comes from various sources such as road salts, leaking oil, and road sediment.  It also comes from your yard in the form of fertilizers, herbicides, leaf litter, grass clippings and pet waste.  There are two general categories of pollution: pollution that comes from a direct or known source and pollution that comes from indirect sources. Direct sources (point source pollution) like factories or waste treatment plants emit contaminated fluids directly into water supplies (usually through a direct line like a pipe). In the United States and other countries, these practices are regulated, but this doesn't mean that pollutants can't be found in our waters.

Indirect sources (or non-point source pollution) enter our water supply from surface runoff and groundwater that contains pollution. Pollution can come directly from our rainwater from atmospheric contaminants such as carbon emissions from our cars and trucks and industrial air emissions. This pollution gathers in rainwater as it falls. It is this rainwater that flows off our roofs, lawns and driveways carrying residue of fertilizer, pesticide, pet waste, gas and oil into the city storm sewers, which lead directly to our lakes, rivers, and streams.  Raingardens are a cost-effective way to reduce the effects of this "nonpoint source pollution" in our watersheds, and to beautify our cities and neighborhoods.

What plants should I use?

Native Roots

Most gardens are best designed with plants that are well adapted to the unique conditions of the garden and your region (such as local native plants or cultivars of those plants).  Raingardens rely on the ground’s ability to absorb and infiltrate water.  Native plants have grown in Minnesota for thousands of years, so they're highly adapated to our weather conditions. This adaptation has resulted in deep and thick root systems and special leaf structures that are well-suited to endure our long winters and our variable periods of drought and heavy rain. Those deep roots deliver water far into the ground so it can be cleaned naturally. Within raingardens, as plants shed the dead portions of their root systems from last year’s growth they leave behind empty channels in the soil that act as "pipes" to help funnel water deeper into the ground rather than run off into the storm sewer. This ground-filtering process helps to clean our precious water and limits the amount of pollutants that would reach a water body through the storm sewer system.

How can I build a raingarden?

Attend one of Metro Blooms' Raingarden Workshops.  Metro Blooms offers seasonal workshops across the metro area which highlight a do-it-yourself approach to raingarden design, installation, and maintenance.