Let’s dig into this form of GSI, and three perennial flowers that are also good for stormwater management.

DYK you can help Philadelphia become cleaner and greener, and even fight climate change? One way to contribute in your neighborhood is to plant a rain garden full of native plants.

Native plants are not only good for pollinators and are known for being low-maintenance, but they can also help with stormwater management – a critical service in cities like Philadelphia, which have a high percentage of impermeable surfaces.

What is a rain garden?

A rain garden is designed to collect stormwater runoff from impervious surfaces such as roofs, walkways, and parking lots. Layered with stone, soil, and vegetation, rain gardens can be tied into sewer systems through an overflow structure, making them flexible solutions for both new developments and retrofits. When storms exceed capacity, an overflow structure directs excess water to the sewer network – usually within 72 hours.

The Philadelphia Water Department offers several programs for homeowners to access green stormwater infrastructure tools, reducing pollution and strain on the system. Rain gardens are typically planted with native, drought-resistant perennials.

Here are three native perennials from PWD to build out your rain garden:

Swamp mallow

Also called “hardy hibiscus,” this perennial has large white, pink, red, or burgundy flowers and has a blooming period for about one month. They prefer a sunny location and moist-to-wet soil. Swamp mallows are well-suited for the middle of a rain garden, as they can withstand standing water.

Blue flag iris

Blue flag irises are native to a wide swath of territory in the northeastern wetlands. They grow between two- to three-feet tall and bloom for about three months in the spring and summer. Blue flag irises are violet with splashes of yellow and are well-suited for areas that are both sunny or have partial shade.

Cardinal flower

The cardinal flower is in the bellflower family and is named for the flowers’ resemblance to Roman Catholic cardinal robes. Their blooms attract butterflies and hummingbirds. Like the other flowers recommended for rain gardens, cardinal flowers do well in moist to wet environments.

For more native plant ideas, see this list from PWD and learn about the department’s Raincheck program for stormwater management.

Note: The idea for this article was generated through conversations with community members during our Green Philly Pop-Up Newsroom at The Oval. Stay tuned for more pop-up-inspired stories, and email info@greenphl.com with any news tips.

Cover photo: 2013 Louis Cook for PWD