Soak Up Showers in a Rain Garden

With all the summer rain we get each year for five months, it might make sense to do something with all that rain rather than have it race down your lawn or driveway into the street picking up pollutants before getting into the waterways unfiltered. At this point, it is no longer just rain water but polluted water.

A rain garden is more than your average flower bed. According to experts, it is a resourceful way to catch stormwater from your gutters and downspouts and use it in a productive way. The greatest amount of storm water on residential properties comes from the roof and the driveway. 

In its most simple design, a rain garden is strategically located near downspouts, next to driveways or sidewalks or out in the yard so it can temporarily capture and hold water for a brief time then filter it before releasing the water into the ground. 

It might help to think of a rain garden as a reverse berm – a shallow depression that collects rain from the yard runoff. It is recommended that a rain garden be installed at the end of a sloping lawn before runoff reaches the ditch or swale. As long as the rain garden is in the path of water and allows for the water to soak in – you have the perfect spot!

Try this: walk around your yard and locate a spot where a rain garden can intercept storm water and allow it to soak into the soil. It might be that soggy area in your yard that collects water – but should not hold that water for long. In a residential setting, rain gardens range in size roughly from 150 to 450 square feet, about four to eight inches deep. Any deeper, you are going to have pooling and mosquitos. 

In my search for better understanding of rain gardens, I visited the Naples Botanical Garden and spent some time with Britt Patterson-Weber, Vice President of Education and Interpretation. I met Britt several years ago when we were called to consult on a project designing a children’s edible garden for the Marco YMCA. 

On a much larger scale, the Naples Botanical Garden “uses nature to take care of nature, using their stormwater treatment system to mimic how water moves across landscape. As stormwater travels through their landscape, land-based contaminants are removed through soil filtration, plant absorption, evaporation and other natural processes.”

They designed bioswales and a rain garden in the parking lot and planted them with a diverse array of native shrubs, trees and grasses. Water filters into the ground where soil purifies it and plant roots absorb it, trapping harmful nitrogen, phosphorus and other pollutants.

A residential rain garden functions in the same way as the large-scale Naples Botanical Garden design. It also functions the same way as the miles of swales we have on Marco Island that act as drainage areas where rainwater is filtered out. The swales reduce pollutants before it enters the waterways but in a much more aesthetically pleasing way.

According to Britt, native plants do very well in rain gardens such as Muhly grass. Add some colorful ground covers and even a small growing tree such as Pond apples. While viewing the Native Botanical Rain Garden by the parking lot, I observed an abundance of pollinators visiting the three types of native grasses. The pink native hibiscus and bright yellow of the dune sunflower gave the landscape a pop of color. 

Britt wanted to emphasize that rain gardens are NOT ponds, wetlands or water gardens. They are dry most of the time and typically hold water only during heavy rainfall. If built correctly, rain gardens will drain within 12 to 48 hours and will not breed mosquitoes.

A recommended resource for a list of native plants for your zip code is at the Institute for Regional Conservation. It will have native plants for your neighborhood and while the list can get overwhelming, here’s some basics to consider: look for native grasses such as Muhly and Fakahatchee; dune sunflowers and hibiscus for color; ground cover such as frog fruit and don’t trim the grasses – let it grow naturally.