A Cape Cod Rain Garden

What is a Rain Garden?

A rain garden is a shallow depression that is planted with deep-rooted native plants and grasses.

Why have a rain garden?

Rainwater that flows over roofs, driveways and other hard surfaces collects pollutants that accumulate from windblown dust, fluids from vehicles, lawn chemicals, and sometimes from the materials of which these surfaces are made. In general, Cape Cod soils are sandy and therefore rainwater percolates down into the groundwater quite readily. Our groundwater is our drinking water and groundwater ultimately flows into our estuaries. Its purity is critically important to the health of Cape Cod.

Plants play an important role in purifying water. Our deep-rooted native grasses, perennials, shrubs and trees are capable of taking in excess nutrients, breaking down pollutants and holding them in place – out of our drinking water. The roots of our lawns only penetrate a few inches into the ground whereas native grasses, such as switch grass, can reach to six feet beneath the surface. Their deep roots promote water infiltration and tolerance of drought.

APCC’s rain garden is an example of one stormwater management technique. It also is a means to showcase the beauty of native plants as well as their ecological value.

Everyone should have a rain garden! Here’s where you, as a homeowner, can start:

Look for a location that will give the rain garden a purpose!

APCC’s rain garden was installed to capture roof runoff from a gutter downspout.

Investigate and determine the suitability of the location

Ask these questions:

All set? DIG
TIP. Use a garden hose or rope or stakes to help layout the shape and dimensions of your garden.

The soil type will determine the depth of excavation and needed organic amendments like leaf mulch that will provide some nutrients and assure some moisture retention in the dry months to keep plants happy.

The APCC garden was excavated by hand to a depth of 18 inches. Because of the lack of organics in our soils (soils are very sandy), we brought in a locally sourced natural leaf mulch, mixed the mulch with the excavated soils in a 50/50 ratio and then returned it to the garden hole.

APCC’s land slopes slightly. In order to insure the rain garden would contain a significant amount of water in a severe storm event, the extra soil we excavated was placed along the lower rim of the garden depression. The mound or berm created was about 4-6inches high. This will serve to hold water in the garden if it were ever to fill.

Getting the rainwater to the garden
There are a couple of different ways to get the water from the downspout to the rain garden (and away from the foundation). One is a trench lined with something water cannot seep through, filled with gravel or river rock to slow the water flow. Alternately, a pvc pipe or gutter extension which can be covered with soil and planted or otherwise hidden.

At APCC, we hand dug a trench that sloped toward the garden that was over six feet away. We lined it with a piece of a rubber pond liner and covered with 3/4inch stone. This directs the water to where we want it, in the garden.

Plant Selection
Determine what the sun exposure is for the site selected. As with planning any garden, it is key to know how much sun the area receives. This will help you choose the appropriate native plants.

These are the plants that APCC has in its rain garden. The APCC garden will receive full sun. All are native, but some are cultivars. A cultivar is a variety of a plant whose desirable traits, such as height and color, have been selected through plant breeding. These are often the native plants you will find at retail nurseries.

The perennials on this list are good nectar producers for pollinators; they are host plants for caterpillars that make butterflies; and they will provide seeds for birds. The red fruits of the winterberry will be food for birds in late winter. And the sedge will help keep weeds down and fill in the bare spaces. All will give “winter interest” in the landscape.

Perennials:

Shrubs

Joe-Pye Weed “Little Joe” (Eupatorium dubium / Eutrochium dubium)

Winterberry “Red Sprite”; the female with berries (Ilex verticillata)

Boneset (Eupatorium perfoliatum)

Winterberry “Jim Dandy”; the male to insure berries

Liatris “Floristan Violet” (Liatris spicata)

Purple Coneflower “Magnus” (Echinacea purpurea)

Groundcover

Black-eyed Susan (Rudbeckia fulgida)

Pennsylvania Sedge (Carex pensylvanica)

Aromatic Aster “October Skies” (Aster / Symphyotrichum oblongifolium)

Path Rush (Juncus tenuis)

Swamp Milkweed (Asclepias incarnata)

Wild Bergamot (Monarda fistulosa)

For more rain garden information see these online sources:
www.raingardennetwork.com
http://nemo.uconn.edu/raingardens
Ecological Landscape Alliance www.ecolandscaping.org – query “rain garden”

Native Plant Initiative

APCC Rain Garden Video

Pesticide Reduction

Printable version of this page

Rain Garden Plant List