Rain Gardens

A rain garden is a shallow, constructed depression that is planted with deep-rooted native plants & grasses. It is located in your landscape to receive runoff from hard surfaces such as a roof, a sidewalk and a driveway. Rain gardens slow down the rush of water from these hard surfaces and hold the water for a short period of time. It allows the water to slowly filter into the ground, rather than running off into nearby streams and lakes.

Landscaped Rain Garden

This landscaped area is planted with wildflowers, native plants, and shrubs. As the rain garden matures, you will enjoy a beautiful patch of flowers and plants that require less maintenance, watering, and chemical inputs than a lawn. They are typically 150 - 300 square feet for a residential area.

Benefits of Rain Gardens

Basically, rain gardens are an inexpensive, simple to implement and environmentally sound solution to urban storm water runoff. A Rain Garden will: filter runoff pollution, recharge local groundwater, protect rivers and streams, remove standing water in your yard, reduce mosquito breeding, create habitat for birds & butterflies, improve water quality and reduce potential of home flooding.

Elements of a Rain Garden

Grass buffer strip around the garden that will slow the velocity of the runoff

Mulch layer will provide a medium for the biological activities to occur and will keep the soil moist

Plants that will use the runoff for moisture and nutrient requirements

Amended Soil layer - where the plant roots collect the moisture and nutrients

Ponding area or depression

A berm - at least six inches of soil or rocks that works like a dam to pond the runoff

Rain Garden Elements Diagram

How Do I Begin?

The Glencar Designers will plan a Rain Garden that will capture the first flush of runoff from your impervious surfaces and will attempt to mimic the functions of a forest.

The design process is the same as designing the rest of your landscape:

  • Initial Meeting – Meet with homeowner/ business owner/ municipality to discuss how the rain garden will work with the existing or proposed landscape of the property.
  • Site Inventory – topography, drainage issues, views, vegetation, soils, etc
  • Site Analysis – Using the inventory we will determine the best locations for the rain garden.
  • Placing the rain garden - We may decide to place it near the house to catch the roof runoff, or place it farther from your house and collect the runoff from your lawn and possibly your driveway.
  • Determining the size of the rain garden and if it will be working individually or as a first flush filter for a rain water harvesting tank.
  • Plant Design – there are different saturation zones within the basin, native plants that do well in each area need to be designed into the plan.

Maintenance & Other Issues

Rain gardens are not completely maintenance-free. It is important to weed, clean-up and re-mulch the garden in the early Spring and Fall.

Mosquitoes – Rain gardens are constructed to drain quickly. This is done to prevent the breeding of Mosquito larvae.