LEARN MORE ABOUT

Rain Gardens

The bursting flowers of a beautiful summer garden invite a weary monarch butterfly to eat and rest. Cool drops of rain patter on the shingles of a roof, snaking their way through downspouts and pooling within a bowl-shaped garden bed. Gravity pulls this rainwater into the earth where it trickles down through layers of soil to join vast reservoirs of water deep underground. What am I describing, you may ask? It’s a rain garden!

What is a rain garden?

A rain garden is a bowl-shaped garden designed to capture and infiltrate stormwater from impervious surfaces. These gardens temporarily store this water, filter it through plant and other organic material, and enable it to soak into the ground on-site rather than running off and entering the storm sewer system.

Credit: Lower Merion Rain Garden Guide.

How do rain gardens work?

Rain gardens function like a sponge, soaking up stormwater and infiltrating it into the ground. When it rains, stormwater is channeled into the rain garden from nearby impervious surfaces like roofs, driveways, and walkways.

Water can enter the garden via a pipe from a downspout, through a depressed channel known as a swale, or via sheet flow from a paved surface. Depending on the rainfall, water might pool in the garden as it infiltrates. If designed properly, the water will disappear within 24 to 48 hours, ensuring that mosquitoes do not breed.

What are the benefits of having a rain garden?

Pollution Control

Rain gardens filter out sediment and other pollutants (like animal waste, brake dust, oils and automotive chemicals) by capturing the first inch of runoff which tends to contain the highest concentration of pollutants. When runoff flows into a rain garden, the water slows and spreads, allowing solids to drop out over a wide area and eventually be absorbed by the soil and plants.

Flooding Protection

Since most storm sewers lead directly to our creeks and streams, stormwater runoff can contribute to dangerous flash-flood conditions during large storm events. Rain gardens help to reduce the runoff leaving residential properties, thus reducing the volume of water flowing directly into our streams.

Water Conservation

By increasing the amount of water that infiltrates into the ground, the gardens help with groundwater recharge. Groundwater is essential for maintaining flow in streams as well as human uses like agriculture and drinking water.

Once they are established, rain gardens only need to be watered during heat waves or long periods without rain. This can help reduce the amount of water you use to irrigate your property, saving you money on your water bills!

Habitat Creation

Rain gardens are planted with deep-rooted native plants which have the ability to infiltrate rainwater in wet times and sense/locate water in dry times. Native plants will support a variety of birds (local and migrating), butterflies, beneficial insects, pollinators, and other wildlife by providing diverse habitat, shelter, and food sources.

Just one rain garden with one inch of rainfall can capture as much as 1,500 gallons of water. Get your friends, family and community involved and see what a difference we could all make towards cleaner water, less erosion, and a healthier ecosystem.

Is my property suitable for a rain garden?

One great benefit of designing your own rain garden is that you can tailor it to the specific resources and conditions of your own property. Whether in full sun or shade, you’ll be able to choose plants which thrive in the environment you have. With that being said, some site conditions are required for a rain garden. The main ones include:

At least 10 ft. from foundation of house (to avoid flooding) and property line.
Adequate distance from large, established trees. Avoid the dripline, the edge of the tree canopy where water would drip from the leaves. This is where the most sensitive roots live.
Ability to channel stormwater from an impervious surface to the site.
Site drains well and doesn’t have issues with standing water.
No utility lines run underneath the site. Call 811 before you dig!

How can I build my own rain garden?

Check out our video at the top of this page for step-by-step guidance on the entire rain garden process! In addition, consider downloading a free copy of the Vermont Rain Garden Manual, a comprehensive guide on rain garden design. For help determining the size of your rain garden, check out this nifty calculator created by the Rain Garden Alliance.

What kinds of plants should I use? Where can I get them?

Native plants are an integral part of rain-garden functionality. These plants generally have long roots that reach deep into the soil, creating passageways for rainwater to easily enter the ground. Plants which are native to your state should be used in your garden - check out the resources below to learn more!

Penn State Extension Guide to Rain Garden Plants

Native Plant Nursery Directory

National Wildlife Foundation - Native Plant Finder

Homegrown National Park - Native Plants Finder

Generally, plants will take at least one to two years to become established in your garden. The size of the container your plants come in will determine how fast they spread - larger will spread faster, smaller will spread slower. If your rain garden is next to a road, we strongly recommend using salt-tolerant native plants. For a list of salt-tolerant native plants, please visit this link.

What is the typical cost of a rain garden?

The cost of a rain garden is dependent on the property’s soil type, the size of roof/driveway/patio draining into a rain garden, and the types of plants chosen. For a self-installed rain garden, expect to pay between $3 and $5 per square foot in plant costs and soil amendments. When working with a landscaping company to design and install your rain garden, the cost will significantly increase to around $10 to $15 per square foot.

Sample Planting Plans

Have you decided that you’d like to construct your own rain garden? One of the first steps to a successful rain garden is devising a planting plan. Plantings plans allow you to visualize your garden and organize your plantings before breaking ground. Some different things to consider in a planting plan include plant height, soil moisture preference, color, seasonal bloom time, and texture. Click here to access some of our previous planting plans.

Maintenance

Maintenance is an often overlooked but vitally important part of ensuring the continued functioning of your rain garden. Throughout the first year of installation, regular weeding and watering are required until plants are fully established. For information and checklists on rain garden maintenance, check out this Rhode Island DEM webpage! You can also check out the Vermont Rain Garden Manual for detailed instructions on the topic.