Landscape - Rain Gardens

Rain gardens are a way to keep excess water runoff from leaving a property while at the same time creating a unique landscape feature. Landscapers should consider incorporating rain gardens into their designs for residential properties. The following is information on creating rain gardens.

Rain gardens can change how we manage storm water in built environments. Instead of providing more paved surfaces, curbs and storm drains to take water (a precious resource) away from our home lawns and landscapes, rain gardens promote the infiltration of water into the pervious surfaces we have remaining in the landscape. They are gardens built with the intention of reducing erosion, flooding, and non-point source pollution by lowering the volume of storm water runoff. Instead of becoming runoff, the rainwater is absorbed back into the ground through the garden.

Construction of rain gardens can vary greatly in complexity and cost. They are commonly built in an area where rain water naturally flows but not in low lying areas that are poorly drained. The garden area required depends on the source; typically sized at 10-20% of the source area. To collect the runoff, grading is sometimes necessary to redirect the water. The garden area is excavated, usually to a depth of four feet but variable with soil type. It is filled with a sandy soil followed by topsoil so the garden lays about six inches below grade. The plants must tolerate standing water (for several days) as well as drought conditions. Hardy, herbaceous, native plants generally perform best in rain gardens.

Perennials:

Aquilegia canadensis, Canadian columbine
Arisaema triphyllum, Jack-in-the-pulpit
Asclepias incarnata, swamp milkweed
Athyrium filix-femina, lady fern
Baptisia australis, false indigo
Boltonia asteroides, boltonia
Carex stipata, tussock sedge
Chelone lyonii, pink turtlehead
Cimicifuga racemosa, black snakeroot
Eupatorium maculatum, Joe-pye weed
Gillenia trifoliata, Bowman’s root
Helianthus angustifolius, swamp sunflower
Hibiscus moscheutos, marsh mallow
Iris cristata, dwarf crested iris
Lobelia cardinalis, cardinal flower
Lobelia siphilitica, great blue lobelia
Meehania cordata, Meehan’s mint
Phlox paniculata, garden phlox
Physostegia virginiana, obedient plant
Spiranthes cernua, nodding lady’s tresses
Stylophorum diphyllum, celandine poppy
Symphyotrichum novae-angliae, N.E. Aster
Symphyotrichum novi-belgii, N.Y. Aster
Tradescantia x andersoniana,
Virginia spiderwort
Vernonia noveboracensis, N.Y. ironweed
Veronicastrum virginicum, Culver’s root

Shrubs:

Cephalanthus occidentalis, buttonbush
Cornus amomum, silky dogwood
Cornus sanguinea, bloodtwig dogwood
Ilex glabra, inkberry holly
Ilex verticillata, winterberry holly
Sambucus canadensis, American elderberry
Viburnum dentatum, arrowwood viburnum

For additional plant suggestions visit http://ag.udel.edu/extension/horticulture/raingarden/raingardenDE.htm

Copied from "Liveable Plants for the Home Landscape", Authors: Susan Barton, University of Delaware, Sarah Deacle, Delaware Center for Horticulture, Gary Schwetz, Delaware Center for Horticulture, and Doug Tallamy, University of Delaware. For the full publication with photos go to http://ag.udel.edu/extension/horticulture/pdf/lowres18spreads.pdf