Rain Gardens
Our design staff is highly trained and certified in sustainable landscaping practices. Learn how we can create a more eco-friendly landscape for you
Bursting with beautiful plantings, Rain gardens are landscaped areas planted with wildflowers and other native vegetation that soak up rain water, mainly from the roof of a house or other building.
As rainwater flows into the garden, it fills with a few inches of water and forms a temporary shallow pond. Over the next few hours, the stored water gently filters into the ground below rather than running off to a storm drain. The garden soil then begins to dry out and return to its natural state.
Rain gardens can also be combined with other sustainable options, such as a rain harvesting system. With proper design and plant selection, this combination of systems can be used to irrigate your property and greatly reduce utility costs.
Key benefits to having your own rain garden:
Helps manage drainage problems and potential flooding issues on your property
Reduces utility usage and costs to water your landscaping
Creates new habitats for wildlife to visit, such as birds and butterflies
Does your part to protect other regional watersheds and the Chesapeake Bay from excess nutrients and pollution
How Rain Gardens Work
Capture
As storm water flows off non-porous surfaces such as roofs and non-permeable driveways, this flow is directed into the rain garden by utilizing roof gutters, drainage pipes, bio-swales or dry creek beds. The garden is shaped like a shallow bowl and is designed to fill up and retain water for up to 1-2 days. During this time, the rain water slowly filters into the soil below and the garden begins to dry up and return to its natural pre-storm state.
The location of the garden can also help solve other water issues around your yard, such as poor drainage next to basement foundations or low-spots/swampy patches.
First Flush
The beginning of any rain storm contains the dirtiest water, as the runoff from roofs, driveways and parking lots picks up and transports the heaviest concentration of sediments and pollutants. Rain gardens help protect local waterways by retaining this storm water on-site, where the plants, vegetation and soil begin to trap and naturally break down these pollutants. This cost-free treatment process is hugely beneficial to protecting downstream creeks and rivers.
Filter
The principal design of the rain garden allows for water capture, retention and the slow release (percolation) of the water downward into the soil and local groundwater aquifer below. This capture and percolation cycle helps protect streams and lakes from pollutants carried by urban stormwater, like lawn fertilizers and pesticides, oil and other fluids that leak from cars, and numerous harmful substances that wash off roofs and paved areas.
Natural remediation of dirty stormwater is an effective, cost-free treatment process to helping the environment. Keeping and treating water on-site has proven so beneficial for the local ecosystems, that many local governments have created programs that reimburse thousands of dollars back to homeowners that participate in rain garden construction projects.
Normal State
In between periods of rainfall the rain garden is designed to have 100% of the water percolate into the soil below, thus leaving a relatively dry garden space. Since native plants are specifically adapted to these local climate conditions (temperature, humidity, rainfall patterns, sun/shade patterns, wildlife, etc.), these plantings require minimal maintenance care. A low effort garden that is hugely beneficial to the environment are two of the biggest reasons that rain gardens are gaining popularity nationwide.
Design + Install Process
Site Analysis
Several site factors are investigated and measured in order to properly design and locate the rain garden for optimal effectiveness. Assessment of peak 25-year storm water flow data, soil percolation rates, lot grading percentage and soil substrate composition are just some of the calculations that determine the potential load applied to the rain garden system. These factors also help determine the best location for garden placement and ultimately how effective it will be.
Excavate
Since these are ‘working’ types of gardens, special design care is needed to construct the proper garden shape, depth and wall angles needed to support a higher water infiltration capacity. Although there is a lot of work happening below the surface, the footprint needed for an effective rain garden is relatively small. Most gardens range in size from 100-200 square feet and excavation is usually less than 4-feet deep.
Soil Amendments
As every local homeowner knows, the typical heavy orange clay and compacted soil conditions found in the Northern Virginia area makes it challenging to successfully grow plants…to say the least. For the best gardens, the underlying soil needs a little help.
During this phase of rain garden construction, we mix organic compost material along with the native soils to achieve optimal growing mediums for the forthcoming plants hosted above. This improved soil composition and texture also allows for the needed water drainage that flows downward through the rain garden and into the local aquifer below.
Zone Planting
Native plants are commonly selected for rain gardens because they are very receptive in the local climate, soil, and water conditions. These plants typically have deep root systems for enhanced water infiltration and drought tolerance, plus they create a habitat for local wildlife.
Plants at the base of the garden will sit in water for longer after rain events, while other plants along the higher sides and edges of the garden have much different root requirements and need to be more drought tolerant. Specific plants are selected and installed in very precise locations to flourish within their individual garden zones. These plant zones work together to create effective filters for the incoming rain water and also allow the overall rain garden to remain self-sustaining.