Rain Gardens

Rain gardens: The benefits of a multi-functional gardens

Did you know rainwater can collect pollutants from surfaces, like your downspouts, driveway, and lawn, and carry them into local streams and rivers?

A rain garden is a natural solution that helps mitigate pollution and pooling of water by providing specific ecological benefits: 

  • Detention: safely collects and temporarily holds stormwater runoff to delay the peak discharge
  • Filtration: filters and consumes pollutants protecting our groundwater
  • Infiltration: allows rain to seep into the ground rather than flow to the storm drain
  • Habitat: supports the local pollinators and other wildlife

 How does it do all that?

 A rain garden is a shallow 6-8” deep basin planted with native plants that are adapted to our locale and specific weather patterns. It captures and detains rainwater and allows it to infiltrate the ground, usually within 24 hours. It mimics and aids to locally restore the natural water cycle which is the process of precipitation and evaporation as well as infiltration and groundwater recharge. As the water passes through the plants’ root zones, microorganisms filter and consume pollutants. 

What types of plants are included in a rain garden?

 Many native plants that are suitable for rain gardens have deep root systems. This allows them to reach water far down in the ground during weeks without rain, while creating channels and conduits to increase the infiltration rate. These native plants offer food and shelter to pollinators and beneficial insects and provide a valuable habitat for birds. 

 As an added benefit, the simple topography of a rain garden, with its purposefully fluctuating water levels, offers the opportunity to establish plants in your garden that may otherwise have not sustained. 

What areas are best suited for a rain garden?

 Almost any lawn can support a rain garden. Aspects of an ideal location are:

  • downhill from downspouts, patio, and/or driveway,
  • 15 feet away from any basement wall,
  • outside of a tree’s drip line (or leaf canopy), 
  • an area without saturated soil.

 It’s necessary to contact “New Jersey One Call” (https://www.nj1-call.org/) to ensure that you don't dig where there are electric, gas, water or sewer lines. You should also perform an infiltration test to confirm that the soil is appropriate for a rain garden. Soil amendments may be made to improve infiltration if needed. The basin size is determined based on the anticipated amount of water that will be directed into the garden. The rain garden has to have an overflow that directs any excess water towards a vegetated area or storm drain. 

Where can I see a local rain garden in action? 

 We are lucky to have a great example of a rain garden in Westfield at Tamaques Park! Built in 2020-2021 with in-kind technical and design assistance from the Rutgers Cooperative Extension Water Resources Program, in partnership with the Department of Public Works and Green Team, the rain garden is located below the central parking lot (by the baseball field) to collect, detain, and infiltrate the runoff generated by the parking lot’s acre of asphalt before it enters the Robinson’s Branch of the Rahway River. 

 Plan a visit to the rain garden at Tamaques Park and see an assortment of plants that provide multi-seasonal interest: magnolia tree, sweet pepperbush shrubs, soft rush, sedges, switchgrass, blazing star, beebalm, turtlehead, and more. We hope it inspires more rain gardens in town!

For more information on how to build your own rain garden, visit the Rain Garden Manual of New Jersey. [http://water.rutgers.edu/Rain_Gardens/RGWebsite/RainGardenManualofNJ.html].