Example of a rain garden, reproduced with permission from the Missouri Botanical Garden.
What is a rain garden?
A rain garden is a special kind of garden designed to collect and absorb runoff storm water. This would be in an area around your home that may have a slope that after a rain would collect water and hold it for awhile.
Top Ten Reasons for having a Rain Garden
- Filter runoff pollution
- Conserve water
- Protect rivers and streams
- Remove standing water in your yard
- Reduce mosquito breeding
- Increase beneficial insects that eliminate pest insects
- Reduce potential of flooding
- Create a habitat for butterflies and birds
- Survive drought seasons
- Recharge local groundwater
Building a rain garden
Find a location
- Place garden at least 10 feet from your home.
- Do not place the garden directly over a septic system or near wells or underground utilities.
- It is better to build the rain garden in full or partial sun, not directly under a big tree.
- Water should only pool in your rain garden for several hours after the rainfall before it is absorbed.
- Do not place rain garden in a part of the yard that already ponds. The goal of the rain garden is to encourage infiltration, and those areas have a slow infiltration.
Decide how to channel the water
- Direct water from downspouts, driveways, patios, or other hard surfaces using gutter extentions, piping, or ditches.
- If expecting heavy flows of water a rock-lined ditch is advisable. Line it with landscape fabric to prevent eroding.
- Stabilize area where water enters the garden with stone to prevent erosion.
Determine size,shape and placement
- Central portion must be six inches below the grade of the surrounding land in order to temporarily hold water.
- Gently slope garden: 1 inch drop for every foot across.
- Rain gardens are best on a flat surface.
- If on a slope, dig more deeply into the high side of the slope to produce a level bottom.
- Build a berm or bump on the lower-end to keep water in the garden.
- Can be circular, kidney-shaped or long and narrow.
Installing
- Use a garden hose, string, or paint can to delineate the outline.
- If possible work with dry soil to avoid soil compaction.
- Loosen the soil at least two feet deep to help plants establish root systems.
- Use extra soil (3 to 6 inches high) to create a berm along edge of the downslope side. Compact this soil to hold the water in the garden.
- If soil is mostly clay, amend soil to make it more permeable.
- Plant your rain garden- work from one side to the other to avoid foot traffic (soil compaction).
- Water your plants.
- Mulch your garden.
Choosing the right plants
- Select plants that can take dry to moist conditions.
- Try to use native, non-invasive species that are resistant to the stress from both periods of wet and dry.
- Start with plants that have a good root structure – not from seed.
- Consider zone hardiness, sun/shade needs, moisture needs, soil type.
- Choose water loving plants for the lowest portion of the garden (center) and dry-tolerant plants for the edges.
- Use native plants whenever possible. Native plants will survive better in our environment.
Plant list for a Rain Garden
Trees
- Red maple, Acer rubrum
- Serviceberry, Amelanchier canadensis
- River birch, Betula nigra
- White ash, Fraxinus americana
- Green ash, Fraxinus virginiana
- Witchhazel, Hammamelis virginiana
- Red cedar, Juniperus virginiana
- Sweetgum, Liquidambar styraciflua
- America Hop hornbeam, Ostrya virginiana
- Pin Oak, Quercus palustris
Shrubs
- Red chokeberry, Aronia arbutfolia
- Black Chokeberry, Aronia melanocarpa
- Inkberry, Ilex glabra
- American Holly, Ilex opaca
- Winterberry holly, Ilex verticillata
- Mountain laurel, Kalmia latifolia
- Northern spicebush, Lindere benzoin
- Virginia creeper, Parthenocissus quinquefolia
- Pinxterbloom azalea, Rhododendron periclymenoides
- Great Rhododendron, Rhododendron maximum
- Elderberry, Sambucus canadensis
- Highbush Blueberry, Vaccinium corymbosium
- Witherod, Viburnum cassinoides
- Northern arrowwood, Viburnum dentatum
Perennials
- Northern maidenhair fern, Adiantum pedatum
- Jack-in-the-pulpit, Arisaema triophyllum
- Wild Columbine, Aquilegia canadensis
- Bushy Aster, Aster dumosus
- New England Aster, Aster novae-angliae
- Glade fern, Deparia acrostichoides
- Sweet Joe-Pye weed, Eupatorium purpureum
- Wintergreen, Gaultheria procumbens
- Wild Geranium, Geranium maculatum
- Cardinal flower, Lobelia cardenalis
- Great blue lobelia, Lobelia siphilitica
- Bee balm, Monarda didyma
- Interrupted Fern, Osmunda claytoniana
- Switchgrass, Panicum virgatum
- White-beard tongue, Penstemon digitalis
- Silverleaf mountain mint, Pycnanthemum incanum
- Wrinkled-leaved goldenrod, Solidago rugosa
- New York fern, Thelypteris noveboracensis
For more information about rain gardens (also known as wetlands), visit the Backyard Conservation website of the US Department of Agriculture.