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Urban Water-Quality Management: Rain Garden Plants

ID

426-043

Authors as Published

Mike Andruczyk, Extension Agent, Chesapeake; Lynnette Swanson, Extension Agent, Norfolk; Laurie Fox, Horticulture Associate, Hampton Roads Agricultural Research and Extension Center; Susan French, Extension Agent, Virginia Beach; Traci Gilland, Extension Agent, Portsmouth.

A rain garden is a landscaped area specially designed to collect rainfall and storm-water runoff. The plants and soil in the rain garden clean pollutants from the water as it seeps into the ground and evaporates back into the atmosphere. For a rain garden to work, plants must be selected, installed, and maintained properly.

Plant Selection

  • Choose plants tolerant of both occasional flooding as well as dry periods.
  • Choose noninvasive plants that are adapted to the local environment.
  • Choose a mixture of species. A good rule of thumb is one plant species for every 10 to 0 square feet. For example – a 140-square-foot garden would have 7 to 14 different plant species.
  • Choose plants for vertical layering – a mix of tall-, medium-, and low-growing species.

Plant Installation

  • Install plants in their proper moisture zones (see Fig. 1).
  • Plant shrubs and perennials in groups of three to five of the same species. Trees can be planted in groups or individually.
  • Plant taller and larger plants in the center or at one end of the garden, depending on the views.
  • Plant shorter plants where they can be seen easily, around the garden edges, in front of larger plants, or underneath taller plants.
  • Space and plant perennials so that their canopies will grow together and cover the ground to minimize weeds.
  • Space and plant trees and shrubs according to their mature size. For example – beautyberry shrubs, that grow to six feet wide, should be planted three feet apart.
  • Planting outside and around the rain garden area helps the garden blend into the overall landscape.
  • More information can be found in Tree and Shrub Planting Guidelines, Virginia Cooperative Extension publication 430-295.
   

figure1.jpg Figure 1. Rain garden.

Maintenance

  • Add two to four inches of organic mulch to the entire newly planted rain garden. Do not cover the crowns of the perennials. Replenish mulch in the fall as needed.
  • Avoid fine cut or lighter weight mulches as they tend to float in wet conditions.
  • Prune any dead, diseased, or damaged plants as soon as the problem is noticed. More information on pruning woody plants can be found in Virginia Cooperative Extension publications 430-455 through 430-462 (see References).
  • Prune the foliage of perennials when they die back for the winter and ornamental grasses before new growth begins in the spring.
  • Remove or spot treat weeds as necessary.
  • Water the garden during its establishment and extended dry periods. One inch of water per week is recommended.

Plant Lists

Trees, shrubs, and perennials are listed with both their common and scientific names. Ask at local garden centers for specific cultivars, varieties, and size at maturity.

Trees
Use trees only in rain gardens larger than 150 square feet.

Alder Alnus serrulata (glutinosa)
Arborvitae Thuja occidentalis
Atlantic White Cedar Chamaecyparis thyoides
Austrian Pine Pinus nigra
Bald Cypress Taxodium distichum
Black Gum Nyssa sylvatica
Carolina Silverbell Halesia tetraptera
Common Persimmon Diospyros virginicus
Dawn Redwood Metasequoia glyptostroboides
Downy Serviceberry Amelanchier arborea
Eastern Redbud Cercis canadensis
Eastern Red Cedar Juniperus virginiana
Green Ash Fraxinus pennsylvanica
Hackberry Celtis occidentalis
Hornbeam Carpinus caroliniana
Japanese Cryptomeria Cryptomeria japonica
Japanese Zelkova Zelkova serrata
Katsura Tree Cercidiphyllum japonicum
Lacebark Elm Ulmus parvifolia
Loblolly Pine Pinus taeda
Planetrees (Sycamores) Platanus spp.
Red Maple Acer rubrum
River Birch Betula nigra
Swamp White Oak Quercus bicolor
Sweetbay Magnolia Magnolia virginiana
Sweetgum Liquidambar styraciflua
Water Oak Quercus nigra
Weeping Willow Salix babylonica/alba
Willow Oak Quercus phellos
Witch Hazel Hamamelis virginiana
Yaupon Holly Ilex vomitoria

Shrubs
American Beautyberry Callicarpa americana
Anise Illicium parvifolium
Arrowwood Viburnum dentatum
Bottlebrush Buckeye Aesculus parviflora
Buttonbush Cephalanthus occidentalis
Carolina Allspice Calycanthus floridus
Chokeberry Aronia arbutifolia
Cranberrybushes Viburnum opulus/trilobum
Devilwood Osmanthus americana
Dogwoods Cornus amomum/racemosam/ sericea
Elderberry Sambucus canadensis
False Indigo Amorpha fruticosa
Fetterbush Leucothoe racemosa
Groundsel Bush Baccharis halimifolia
Highbush Blueberry Vaccinium corymbosum
Inkberry Ilex glabra
Leucothoes Leucothoe axillaris/fontanesiana
Oakleaf Hydrangea Hydrangea quercifolia
Possumhaw Ilex decidua
Rose of Sharon Hibiscus syriacus
Shadblow Serviceberry Amelanchier canadensis
Spicebush Lindera benzoin
Steeplebush Spiraea tomentosa
Summersweet Clethra Clethra alnifolia
Swamp Azalea Rhododendron viscosum
Swamp Rose Rosa palustris
Virginia Sweetspire Itea virginica
Wax Myrtles Myrica cerifera/pennsylvanicum
Willows Salix caprea/discolor/matsudana sachalinensis/purpurea
Winterberry Ilex verticillata

Perennials
Arrowhead Sagittaria latifola
Asters Aster spp.
Beardtongue Penstemon digitalis
Beebalm Monarda didyma
Blackeyed Susan Rudbeckia hirta
Blue Lobelia Lobelia siphilitica
Bluestar Amsonia tabernaemontana
Calla Lily Zantedeschia spp.
Canna Lily Canna spp.
Cardinal Flower Lobelia cardinalis
Crinum Lily Crinum spp.
Daylilies Hemerocallis spp.
Gingers Hedychium spp.
Goldenrod Solidago flexicaulis
Hardy Begonia Begonia grandis
Hibiscus Hibiscus coccineus/moscheutos
Ironweed Vernonia noveboracensis
Irises Iris lousiana/pseudacorus/versicolor/ virginica
Joe-Pye Weed Eupatorium spp.
Leopard Plant Ligularia tussilaginea
Liatris Liatris spicata
Lilyturf Liriope muscari
Lizard Tail Saururus cernuus
Lungwort Pulmonaria spp.
Marsh Marigold Caltha palustris
Monkey Flower Mimulus ringens
Obedient Plant Physotegia virginiana
Pickerelweed Pontederia cordata
Plantain Lily Hosta spp.
Primroses Primula spp.
Rain Lilies Zephyranthes spp.
Red Columbine Aquilegia canadensis
Siberian Bugloss Brunnera macrophylla
Spiderwort Tradescantia spp.
Strawberry Begonia Saxifraga stolonifera
Swamp Milkweed Asclepias incarnata
Swamp Sunflower Helianthus angustifolius
Turtleheads Chelone lyonii/obliqua
Virginia Bluebells Mertensia virginica
Wild Ginger Asarum canadense
Windflowers Anemone

Ferns
Christmas Fern Polystichum acrostichoides
Cinnamon Fern Osmunda cinnamomea
Holly Fern Cyrtomium falcatum
Japanese Painted Fern Athyrium nipponicum
Lady Fern Athyrium felix-femina
Royal Fern Osmunda regalis
Tassel Fern Polystichum braunii
Wood Ferns Dryopteris spp.

Grasses and Grass-like
Broom Sedge Andropogon virginicus
Feather Reed Grass Calamagrostis acutiflora
Foxtail Grass Alopecurus pratensis
Rushes Juncus spp.
Sedges Carex spp.
Sweetflag Acorus spp.
Switchgrass Panicum virgatum

Groundcovers
Bugleweed Ajuga spp.
Foamflower Tiarella cordifolia
Green and Gold Chrysogonum virginianum
Lilyturf Liriope spicata
Mazus Mazus reptans
Plumbago Ceratostigma plumbaginoides
St. Johnswort Hypericum calycinum

 

References

Rain Gardens, A Landscape Tool to Improve Water Quality; Virginia Department of Forestry Publication VDOF 000127, http://www.dof.virginia.gov/

Rain Gardens, Virginia Department of Forestry, http://www.dof.virginia.gov/rfb/rain-gardens.shtml

Backyard Rain Gardens, North Carolina Cooperative Extension, http://www.bae.ncsu.edu/topic/raingarden/

Rain Gardens, University of Wisconsi-Extension, http://clean-water.uwex.edu/pubs/raingarden/index.html

Rain Gardens, Rainscapes, http://209.142.214.237/rainscapes/garden.htm

Rain Gardens of West Michigan, http://www.raingardens.org/Index.php

Tree and Shrub Planting Guidelines, Virginia Cooperative Extension publication 430-295, http://pubs.ext.vt.edu/430-295/

A Guide to Successful Pruning: Pruning Basics and Tools, Virginia Cooperative Extension publication 430-455, http://pubs.ext.vt.edu/430-455/

A Guide to Successful Pruning, Pruning Deciduous Trees, Virginia Cooperative Extension publication 430-456, http://pubs.ext.vt.edu/430-456/

A Guide to Successful Pruning, Pruning Evergreen Trees, Virginia Cooperative Extension publication 430-457, http://pubs.ext.vt.edu/430-457/

A Guide to Successful Pruning: Stop Topping Trees!, Virginia Cooperative Extension publication 430-458, http://pubs.ext.vt.edu/430-458/

A Guide to Successful Pruning, Pruning Shrubs, Virginia Cooperative Extension publication 430-459, http://pubs.ext.vt.edu/430-459/

A Guide to Successful Pruning, Decidous Tree Pruning Calendar, Virginia Cooperative Extension publication 430-460, http://pubs.ext.vt.edu/430-460/

A Guide to Successful Pruning, Evergreen Tree Pruning Calendar, Virginia Cooperative Extension publication 430-461, http://pubs.ext.vt.edu/430-461/

A Guide to Successful Pruning, Shrub Pruning Calendar, Virginia Cooperative Extension publication 430-462, http://pubs.ext.vt.edu/430-462/

Editorial Contributors

Barry Fox, Extension Specialist, Virginia State University

Adria Bordas, Virginia Cooperative Extension Agent Fairfax County

Karen Carter, Virginia Cooperative Extension Agent Henrico County

JoAnne Gordon, Horticulturist, City of Norfolk

Rights


Virginia Cooperative Extension materials are available for public use, re-print, or citation without further permission, provided the use includes credit to the author and to Virginia Cooperative Extension, Virginia Tech, and Virginia State University.

Publisher

Issued in furtherance of Cooperative Extension work, Virginia Polytechnic Institute and State University, Virginia State University, and the U.S. Department of Agriculture cooperating. Edwin J. Jones, Director, Virginia Cooperative Extension, Virginia Tech, Blacksburg; Jewel E. Hairston, Administrator, 1890 Extension Program, Virginia State, Petersburg.

Date

May 1, 2009