Rain Garden Basics

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A rain garden is a carefully planned depression in the landscape that collects rainwater and snowmelt. The garden will capture stormwater and allow it to soak into the ground rather than become runoff. Stormwater that is not captured will move across the landscape has the potential to pick up pollutants (lawn, fertilizers, pet waste, car fluids, and more!) and carry them directly to area waterways.

In this section:


Anatomy of a Rain Garden 

Anatomy of a rain garden image - large  

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Benefits of a Rain Garden
 

Rain gardens have many perks beyond treating stormwater runoff:

  • Insects, birds, and other wildlife will feed, rest, or live in the garden.
  • Drought resistant plants will look great all summer long, even when turfgrass is dormant from lack of water.
  • There is no need to fertilize native plants because they are adapted to our conditions and will grow well without it.
  • Where there is a garden, there is no mowing!

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Maintenance Requirements

Native plants require very little maintenance, thus they reduce demands on your wallet and time!

  • First two years:
    • Weeding as needed. A 3 inch layer of mulch, preferably double-shredded hardwood mulch, will help keep weeds at bay and make removal of any new weeds much easier.
    • Watering once a week if there has been less than an inch of rain. Ensuring an inch of water each week will help new plants establish the deep, extensive roots that will help pull stormwater into the ground.
    • Cut last year's growth. Leaving plants through the winter will provide food and habitat for wildlife. In the spring, cut off old growth so the plant can grow uninhibited.
  • After rain garden is established:
    • Weeding twice per season
    • Splitting plants once per season
    • Mulching as needed, typically every couple years
    • Replacing plants as needed. Many native plants are self-seeding and will not need any replacement. A few species will need to be replaced after about 5 years.
    • Watering only in the case of extreme drought.
    • Cut last year's growth. Leaving plants through the winter will provide food and habitat for wildlife. In the spring, cut off old growth so the plant can grow uninhibited.

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Planning Your Garden

Each rain garden is unique and is designed for specific soil types and landscapes. Proper planning is essential for creating a functional rain garden.

  • Infiltration test
    This test will determine how much water will soak into the soils within in a 24 hour period, thereby influencing the depth of the rain garden. Soils can vary greatly from one side of the yard to the other, so it is important to do this test as close to the actual garden site as possible. The rain garden should be no deeper than the amount of water the soils can infiltrate in a 24 hour period - any deeper and the garden could have standing water and become a breeding ground for mosquitos. 
  • Location, location, location
    Rain gardens are designed to temporarily hold stormwater so it can soak into the ground. It is recommended that these gardens be placed at least 20 feet away from a building with a foundation. It is easiest to install a rain garden where stormwater runoff naturally flow; however, there are methods of directing water to a desired location.

  • Pick your plants
    Native wildflowers and grasses are ideal for rain gardens as they require less maintenance and thrive in our climate. The deep, extensive roots of native plants will pull stormwater into the ground after it collects in the rain garden and can help stabilize the soils. There are beautiful native plants for every location, including shady sites.

  • Stay safe
    Contact Gopher State One Call to locate all utility lines on the property before digging: 800-252-1166 or www.gopherstateonecall.org

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Rain Garden Resources

Visit the following websites to find valuable resources to help guide your planning process:

  • Realize Rain Gardens Rochester: This cost-share grant program helps fund the installation of rain gardens across the City of Rochester. Available resources include: provided include: grant information, planning guides, and a photo tour of rain gardens in Rochester.

  • Blue Thumb - Planting for Clean Water: This Twin Cities based award-winning collaborative program encourages homeowners to use native plant gardening, rain gardens, and shoreline stabilization to reduce runoff from their home landscape in an effort  to improve water quality. Available resources include: a guide to year round yard care,  partner map, and plant selector tool.

  • Metro Blooms: This private non-profit volunteer-based education organization promotes environmentally sound gardening and landscaping practices to improve the health of land and water resources. Available resources include: rain garden installation videos and an urban gardeners guide with tips on picking plants and maintenance.

The Rain Garden Landscape Design Manual was created by the South Zumbro Watershed Partnership and can help guide you through the process of creating a rain garden.

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