Rain Garden

Before the flowers of May, the rains of April provide an opportunity to observe the behavior of water in your landscape. Water pooling, rapid runoff and soil erosion are all invitations to explore a sustainable method of water management. Planting a rain garden is a naturally aesthetic and highly functional water management system that provides many benefits beyond beauty!

Rain Garden Benefits

  • Water conservation
    Rain gardens capture and hold rain water allowing it to slowly soak into the ground, recharging groundwater sources which feed your entire landscape.
  • Protect rivers and streams
    Rain gardens divert water away from storm sewers and filter out sediment and pollutants that might otherwise flow into rivers and streams.
  • Promote biodiversity and wildlife
    Rain gardens are built using native plants which attract and support a variety of native pollinators, birds and animals.
  • Reduce risk of localized flooding
    A well placed rain garden can reduce the amount of rain that flows into your basement or sewer.
  • Reduce landscape erosion
    Because of their deep root systems, rain garden plants help hold soil in its’ place.
  • Improve drainage
    Rain gardens soak up 30% more water than a turf lawn which means, less water pooling, runoff and mud.
  • Reduce mosquito breeding
    Pooled water is prime mosquito breeding ground, in Minnesota that may be reason enough to build a rain garden!

Rain Garden Basics

Put simply, a rain garden is a garden built on a downward slope or low lying area consisting of native plants that collect runoff from impermeable surfaces. Their design can be simple with just a few native plants en masse or more intricate with a greater variety of plants and design elements. Interested in a rain garden design, we are happy to help, write info@Bloomonmn.com for more information. Alternatively, if you are ready to literally “dig-in”, read on for more information on rain garden design.

Location, Location, Location

A rain garden’s greatest benefit is capturing runoff, so choose a location where runoff is actively observed and at least ten feet away from your foundation. Look for low lying areas or slopes where water tends to pool or runs off towards the road, your driveway or waterways. Take a test of your soil, your soil needs to be porous in order for the rain garden to function appropriately. Dig a hole about ten inches deep and fill with water, if the water is absorbed within 48 hours your location is suitable. You may also amend the soil with soil perfector which permanently improves drainage and moisture retention.

Size and Design

Most rain gardens are between 100 and 300 square feet however, the size of the your rain garden is dependent upon the size of the impermeable structure runoff is being collected from. A rain garden can handle runoff from a surface three times its’ size. For example, if your driveway is 40 feet long by 10 feet wide (400 square feet), a 130 square foot rain garden would be sufficient to handle the runoff. It is recommended to build multiple rain gardens for very large surfaces such as rooftops, capturing water from multiple down spouts.

The shape of your rain garden can be anything you want it to be. Crescent and kidney shapes are attractive and soften the landscape whereas long, narrow gardens may be better suited along sidewalks or between structures.


The commonality of all rain garden plants is their deep root system and adaptability to their environment. Contrary to popular belief, many plants can be used in a rain garden and not just wetland plants. Where in your garden the plants are planted determines what plants are planted. Generally, rain gardens are divided into three parts or zones:

  • Zone 1 | Wet – The lowest point of the garden for plants that prefer wet conditions.
  • Zone 2 | Semi-Wet – The mid-range or middle of the garden for plants that tolerate occasional standing water.
  • Zone 3 | Dry – The top-side, transitional space for plants that require sharper drainage and drier conditions.

Also, of equal importance is how much sunlight the site receives to determine what plants should be used.

Sambucus canadensis (Elderberry)
Zone 1
Veronicastrum virginicum (Culver’s Root) Zone 2
Asclepias incarnata (Swamp Milkweed)
Zone 3

Now that you have identified your site, sketched your design and selected some plants, enjoy the rainy days of April and the time it gives to plan your beautiful and functional rain garden. When it is time to plant, stop into GrowHaus and browse our vast selection of native rain garden plants.

For more information and an example rain garden design, click here. You can also visit the University of Minnesota website for more detailed information and a complete list of zone hardy plants before your visit to the Garden Center.

Happy Rain Planting!