Introducing the Pocket Rain Garden
By Elizabeth Cornell Fake, Fairfax Master Gardener
In Virginia, we usually have our own rainy season in late May and early June. The rain water torrents down roofs and gutters, splashing off cement walks and driveways and winding its way down into the storm sewers. Environmentalists agree that the unfiltered, polluted water pouring off impervious surfaces is the major source of pollution for our nation’s waterways. A pocket rain garden is one way to manage our own home landscapes, by capturing and filtering the runoff that is so threatening to our rivers and oceans.
As usual, adding this kind of landscape feature to your yard will take some study, planning and, of course, back-breaking labor. To start, there are five parts to a successful rain garden project that require investigation and planning in progression
- Part 1 — a ponding area or depression that will serve as the container for the runoff
- Part 2 — a soil bed at the bottom of the depression that permits good drainage and quality soil to nourish the vegetation
- Part 3 — a berm or barrier made of soil or rocks to slow the speed of the runoff and keep the water in the container
- Part 4 — a selection of native plants including perennials, shrubs or even a tree
- Part 5 — a thick layer of mulch to support the growth of the plants and retain moisture during periods of drought
For construction, measure about 10 feet from the foundation of your house and then, using a fluorescent spray paint, mark off a garden area that is perpendicular to the area of the runoff. The size of the garden is dependent on soil composition, since a more porous soil, such as a sand/silt mix, can be smaller because the water will pour through more quickly than a denser clay-mix soil. If the soil is compact and takes more time to drain, you will need a larger space to allow for proper drainage.
Before you lift a shovel to dig anything, be sure you have called Miss Utility to make sure there are no underground utilities at the selected garden site. Then call in a crew to help you dig the 6-inch-deep soil basin, create the berm and plant a selection of native perennials and shrubs. Suggested native plantings for our area of Northern Virginia include: Elderberry (Sambuca canadensis), Black chokecherry (Aronia melanocarpia), Winterberry holly (Ilex verticillata), Arrowwood viburnum (Viburnum dentatum), Virginia sweetspire (Itea virginica), Joe Pye weed (Eupatorium fistulosum), Switchgrass (Panicum virgatatum), Obedient plant (Physostegia virginiana) and Black-eyed susan (Rudbeckia hirta).
As a final step, cover the garden with a 3- to 4-inch carpet of double- or triple-shredded hard bark, cedar mulch. Be sure to allow open space around each plant for optimal watering. Water as required to establish the plants, and then let the rain take over the project. After all, it is a pocket rain garden!
• Clemson Extension Virtual Rain Garden, Clemson University Cooperative Extension Service,
Clemson University Center for Watershed Excellence
• Rain Gardens, Technical Guide 2014-5, State of Virginia, Department of Forestry
• Rain Garden Design and Construction — a Northern Virginia Homeowner’s Guide, Northern Virginia Soil
and Water Conservation District