Fall Is For Planting: Rain Garden Resources From Penn State Extension

By: Andy Yencha, Extension Educator & Jodi Sulpizio, Master Watershed Steward Coordinator York County

Penn State Extension has many resources for property owners, municipal staff, and anyone else who wants to learn more about building, planting, and maintaining rain gardens.

Rain gardens are landscape features that an increasing number of homeowners, businesses, and local governments are installing to reduce the stormwater that flows off their properties. 

These infiltration basins come in many shapes and sizes, but all rain gardens collect stormwater runoff from roofs, parking lots, or other hard surfaces so some of this water will soak into the ground instead of flowing onto nearby properties or into municipal storm sewer systems. 

Rain gardens contain plants (natives preferred) that provide many functions and benefits. The plants absorb stormwater, remove runoff pollutants, provide habitat for pollinators and other wildlife, and beautify the places where we live and work. 

Penn State Extension has developed a rich collection of materials related to building, planting, and maintaining rain gardens.  

Why Build a Rain Garden 

Rain gardens manage stormwater which is a growing problem in Pennsylvania and many other parts of the United States. Excess runoff triggers erosion, destroys aquatic habitat, pollutes water, and causes flooding and flood related property damage. Rain gardens can help fix these problems.

-- What is Stormwater (LearnNow Video) 

-- Why Should I Care About Stormwater? (LearnNow Video) 

-- Rain Gardens Can Help Slow the Flow 

-- Roadside Guide to Clean Water: Rain Gardens  

-- Infiltrating Stormwater  

How to Build a Rain Garden 

Basic rain gardens can be installed in residential areas to capture modest amounts of stormwater from downspouts, driveways, and backyard patios. 

These homeowner gardens are often small (under 100 square feet), just a few inches deep and very often do not require soil amendments if the existing ground drains well enough. 

Complex rain gardens, sometimes containing special soil mixes and underground drainage, are increasingly found in urban areas to capture heavy runoff flows from parking lots, roads, and commercial buildings. 

Before digging your rain garden, Penn State Extension recommends doing a simple percolation test to ensure adequate drainage. Contact your County Extension office for more information.

-- An Introduction to Rain Gardens 

-- Rain Gardens – The Basics  

-- Rain Gardens (LearnNow Video) 

-- Rain Gardens (BioRetention Cells) – a Stormwater BMP (Best Management Practice) 

Rain Garden Plants

Rain gardens are called “gardens” because they contain a variety of plants that help them manage stormwater and provide other important benefits. 

Plant selection, especially for the do-it-yourselfers with minimal gardening knowledge, can seem overwhelming. 

Penn State Extension has several resources to make the process easier, including information about soil testing which, if performed, can provide useful information on soil fertility and pH that might influence your final plant selection.

-- Soil Testing 

-- Rain Gardens – The Plants 

-- Why Use Native Plants 

-- Recommended Trees and Shrubs 

-- Recommended Herbaceous Perennials 

-- Planting Your Rain Garden (Webinar Recording)

Plant Field Sheets

Plant selection is especially important. Matching plants with the sunlight, soil, and moisture conditions of your rain garden is the first step in the plant selection process. 

Penn State Extension Educators recommended considering plants with varying characteristics to make your garden attractive through all seasons. 

Choose plants based on factors like mature height, overall appearance, bloom time and color, spreading habits, any unique benefits they offer such as providing food for pollinators, and availability at local garden centers or through mail order vendors. 

Maintaining rain gardens, especially proper plant identification through all four seasons so they do not get accidentally removed as weeds, can be challenging at times. Therefore, it is important to know what each plant looks like during the various stages of growth. 

We created rain garden plant fact sheets to provide more information as you begin to select, plant, and maintain your rain gardens. 

The plants are arranged by preferred moisture conditions. Wet/Moist zone plants prefer places that are always wet and may not do well in gardens with excellent drainage. 

Moist zone plants can tolerate some dry conditions but do best in sites where soils are usually moist, but not consistently saturated. 

Moist/Dry zone plants are the workhorses of most rain gardens because they can tolerate both wet and dry conditions. 

Dry zone plants can survive occasionally being wet but do best in well drained soils. These plants are often planted on the high sides of rain gardens.

-- Wet/Moist Zone: Swamp Milkweed; Pink Turtlehead; White Turtlehead; Marsh Marigold; Blue Flag Iris; Golden Ragwort; Cardinal Flower; Smooth Aster; Golden Alexander

-- Moist Zone: Great Blue Lobelia; Bee Balm; New England Aster; Blazing Star

-- Moist/Dry Zone: Wild Geranium; Threadleaf Bluestar

-- Dry Zone: Butterfly Weed; Purple Coneflower

More fact sheets will be added as they are completed. To date, we have included common herbaceous plants for rain gardens. Recommended trees and shrubs will be done in the future.

(Reprinted from the latest Penn State Extension Watershed Winds newsletter.  Click Here to sign up for your own copy (bottom of page).)

Resource Links:

-- Pollinator Gardens: Help Encourage Ecological Diversity In Your Own Backyard [Videos]

-- Gardening For Butterflies: Penn State Extension

-- Planting For Pollinators: Penn State Extension

-- Penn State Extension Master Gardeners

-- Penn State Pollinator Garden Certification

-- DCNR Blog: Bring Life To Your Yard With Native Plants - Start With These; Garden Templates; Where To Buy

-- DCNR Blog: Growing Native Plants To Thwart Invasive Species

-- DCNR Blog: Good Weeds (Native Plants)

-- PennDOT: Adopt And Beautify - Keystone Pollinator Habitat

Related Articles - Penn State Extension:

-- Celebrate Riparian Buffer Month In October With Penn State Extension, Chesapeake Conservation Landscaping Council, Local Groups - By Kristen Koch, Penn State Agriculture & Environment Center

-- Master Watershed Stewards Program Expands Across Pennsylvania Wilds

-- Master Watershed Stewards Complete 5th Annual Storm Drain Art Contest In York

-- Growing Great Buffers - Video

-- Volunteers Worked Together To Remove 600 Pounds Of Trash From Lake Erie Watershed

-- Unpacking The Plastics Pollution Problem

[Posted: September 22, 2022]  PA Environment Digest