Rain Gardens / Bioretention / Bioswales
A rain garden is a functional landscaping technique that can beautify your property as well as help filter and slow the flow of stormwater.
Rain gardens are saucer shaped gardens that water flows into that are planted with grasses, flowers, shrubs, and sometimes small trees. They soak up water while providing wildlife habitat. The soils and basin fills with water for a short amount of time before soaking back into the surrounding soil. Plants used in these gardens are adapted to survive in short periods of flooding as well as dry soils in between storms.
Rain gardens often collect water from roof gutters, driveways, and sidewalks. Rain gardens are common around homes and townhomes.
What is a Bioretention Garden? A Bioswale?
Bioretention gardens are often used interchangeably with rain gardens. They are almost the same thing, except one main difference - bioretention gardens have underneath drainage, while rain gardens depend on the soil for proper drainage. Rain gardens are built with native soils mixed with compost or a special soil mix, while bioretention basins have special soil mix and gravel beneath the soil to hold more water. Furthermore, rain gardens do not have a buried perforated pipe.
A bioswale is similar to a bioretention area in the way it is designed with layers of vegetation, soil and a perforated pipe within the bottom stone layer. Bioswales typically are located along a roadway and can be planted like gardens or covered in turfgrass.
Why Should I Install a Rain Garden?
Rain gardens allow about 30% more rainwater to soak into the ground than traditional lawns. Since rain gardens capture stormwater onsite, they can reduce the harmful effects to streams caused by large and rapid stormwater flows.
Rain gardens offer multiple benefits to the community and the local environment, which include:
However, the most important reason to install a rain garden may be that you are doing your part to help the environment and protect your local streams and the Chesapeake Bay.
Is a Rain Garden Right for Me?
Not all sites are suitable for a rain garden, and a conservation landscape may be a more appropriate project. If you have poorly drained soils, steep slopes, or space constraints, you should consider conservation landscaping.
How to Assess Your Property
Take some time to walk around your property to assess the drainage conditions. The best time to make your observations is when it is raining, so that you can see where the rain lands and where it flows. Consider these questions to help you identify where a rain garden could be placed to capture stormwater runoff on your property:
Once you have identified the pattern of drainage on your property, you can narrow down the potential rain garden locations on your property. The RainScapes Rain Garden Guide has the completed steps for assessing your property on Page 3 as well as the ideas for designing and building your garden.
Ready to move ahead with installing a rain garden?
There are a lot of decisions that need to be made with your rain garden after the assessment is complete.
The RainScapes Rain Garden Guide (below) has suggestions and useful information on how to best make the necessary decisions. The RainScapes program has knowledgeable and helpful staff who can help you through the process as well as the RainScapes Rewards Rebates program with great financial incentives for installing the garden.
Download the RainScapes Rain Garden Guide (PDF, 785KB)
Maintaining Rain Gardens and Bioretention Basins
By maintaining your practice, you are doing your part to help the environment and protect your local streams and the Chesapeake Bay.
DEP can answer your questions and provide additional guidance about maintaining your garden. Please email firstname.lastname@example.org or call the Montgomery County Customer Service Center at 3-1-1.
Help Maintain Right-of-Way Rain Gardens and Green Streets
Do you have a rain garden or other stormwater management facility in the right-of-ways of your neighborhood? You can help DEP by performing regular maintenance activities.
Want to learn more about maintaining Right-of-Way Rain Gardens and Green Streets? Email email@example.com
Rain Gardens in the Stormwater Facilities Maintenance Program
The Stormwater Facilities Maintenance Program is responsible for maintaining all public stormwater facilities as well as all private facilities that transfered their maintenance to the County. The program also maintains facilities that were required as part of the Department of Planning permits.
Can I remove my rain garden after installation?
No, you cannot remove any facilities that were part of your building installation - these are permitted structures and DEP maintains a database of these facility locations as part of the Stormwater Facility Maintenance Program. DEP may perform a maintenance inspection of your practice if it is a permitted structure. Property owners must contact DEP before any major changes can be performed to the structure.
Rebates, Resources and Financial Incentives
Interested in installing a rain garden? The County offers incentives to help make the decision a little easier.
The RainScapes Rewards Rebates Program
The County offers technical and financial assistance (in the form of rebates) to encourage property owners to implement RainScapes techniques on their property, including rain gardens.
To participate, your property must be located in Montgomery County, outside of the municipal limits of the City of Rockville, City of Takoma Park, or City of Gaithersburg. Projects are not eligible if they are associated with permit approval requirements for new building construction, additions, or renovations.
The program is funded each fiscal year (The FY begins July 1 and ends June 30). Annual funds for the programs are limited, so rebates will be awarded on a first-come-first-served basis.
The RainScapes program also provides technical assistance to help with the installation of your rain garden. They have a wealth of information, expertise and want to help!
The Water Quality Protection Charge Credit Program
After you have installed your rain garden, you are now eligible to receive a credit off your annual Water Quality Protection Charge (found on your yearly property tax bill). The credit provides an incentive for maintaining your rain garden and other stormwater management practices.
You must apply for the WQPC credit separately – the credit will not be provided to you automatically.
Residential property owners can receive up to 50% off their WQPC depending on the type and size of stormwater management practices on the property.
Non-residential and multi-family properties can receive up to 50-60% off their WQPC depending on the type and size of the stormwater management practices on the property.