Rain Gardens and Bio-swales can be a large part of sustainable Low Impact Development. Incorporating these design elements into your landscapes will help to take up excess water and filter it before it enters groundwater systems.
These areas mimic wetland natural areas and sometimes natural forested areas, with the mix and placement of plants. The effect is quiet lovely. Rain gardens and bio-swales can include a variety of plants including trees, shrubs, grasses and herbaceous plants. See our list below for more details.
Rain Gardens
A rain garden is a shallow landscape depression with native soil or a soil mix and plants that can capture stormwater from small, adjacent contributing areas. They generally are areas with sloping sides so different plants can be employed at various levels, depending on how much moisture they can retain and use. Plants in rain gardens can withstand standing water and often have systems that work to absorb excess water, rather than allowing it to runoff and erode native soils.
Bio-swales
Biorention swales are similar to rain gardens in that they are a depressed area of plants and soil, used to catch excess stormwater and runoff. Bio-swales are designed with even more drainage solutions in mind, as part of a system that can handle large quantities of runoff when other systems are flooded. Bio-swales are often built in low-lying areas where water tends to naturally collect. Plants can be used to take up some of the excess and to create a handsome and hospitable landscape environment. However, optional under-drains can be included to help direct excess water to proper storm drains. Additionally, gradient controls, such as check dams, gravel mulch and catch basins, are used to reduce flow and manage erosion and sediment buildup.
Where to Use Them
Rain gardens and bio-swales can be employed on a small or large scale. These can be used in both residential and commercial properties to prevent flooding, improve drainage and deal with excess water on a property. They do not need to take up much space. Rain gardens can be installed in parking lot and round-about islands. They work well in landscaped areas of apartment complexes and shopping centers. Bio-swales work well along road ways and ditches, where water naturally pools.
Order Now
Take a look at our list of perennials, grasses, shrubs and other plants that are compatible with Low Impact Development. You can order any of these plants today. Give us a call with your orders and questions at 1-866-816-5080
Zone 1 Trees
Species/Common Name | Exposure | Mature Size | Bloom Time | Comments |
---|---|---|---|---|
Alnus rubra
Red alder |
Sun/part shade | 30′-120′ high and 25′ wide | Highly adaptable, drought tolerant, nitrogen fixer | |
Salix lucida
Pacific willow |
Sun | 40′-60′ high and 30′ wide | Tolerates seasonal flooding, do not plant near pavement or underground structures | |
Fraxinus latifolia
Oregon ash |
Sun/part shade | 40′-80′ high and 30′ wide | Flood tolerant, small green-white flowers | |
Malus fusca
Pacific crabapple |
Sun/part shade | To 40′ high and 35′ wide | Spring | Tolerant of soil saturation, produces fruit, not recommended to get in larger than #5 pot. |
Zone 1 Shrubs
Species/Common Name | Exposure | Mature Size | Bloom Time | Comments |
---|---|---|---|---|
Lonicera involucrata
Black twinberry |
Part shade/shade | 2′-8′ high | April-May | Tolerant of shallow flooding, yellow tubular flowers attract hummingbirds |
*Myrica californica
Pacific wax myrtle |
Sun/part shade | To 30′ high | May-June | Inconspicuous spring flowers, drought tolerant once established |
Physocarpus capitatus
Pacific ninebark |
Sun/part shade | 6′-13′ high | May-June | Drought tolerant, white flowers, seeds persist into winter |
Rosa pisocarpa
Clustered wild rose |
Sun/part shade | 6′-8′ high | May-July | Tolerates seasonal flooding but also tolerant of dry conditions, pink clustered flowers |
Salix purpurea ‘Nana’
Dwarf arctic willow |
Sun/part shade | 3′-5′ high
|
Grows well in poor soils, moderately drought tolerant, small yellow flowers | |
Spiraea douglasii
Douglas spiraea |
Sun/part shade | 4′-7′ high | Takes seasonal inundation, spikes of small pink flower clusters |
Zone 1 Emergents
Species/Common Name | Exposure | Mature Size | Bloom Time | Comments |
---|---|---|---|---|
Carex obnupta
Slough sedge |
Sun/part shade | 1′-5′ high | Takes seasonally saturated soils, shiny foliage, excellent soil binder and drought tolerant | |
Carex stipata
Sawbeak sedge |
Part shade | 10â€-3′ high | Takes wet soil, excellent soil binder | |
*Juncus effuses
Common rush |
Sun/part shade | 1′-2′ high | Summer | Hardy and adaptable, drought tolerant, small non showy flowers |
Juncus ensifolius
Daggerleaf rush |
Sun | 12â€-18†high | Wet soils, shallow water, excellent soil binder | |
Juncus tenuis
Slender rush |
Sun | .5′-2.5′ high | Moist soils, tufted perennial | |
Scirpus acutus
Hardstem bulrush |
Sun | 4′-8′ high | Favors prolonged inundation, excellent soil binder | |
Scirpus microcarpus
Small-fruited bulrush |
Sun/shade | 2′-4′ high | Tolerates prolonged inundation, good soil binder, drought tolerant |
Zone 2 Trees
Species/Common Name | Exposure | Mature Size | Bloom Time | Comments |
---|---|---|---|---|
Acer truncatum
Pacific, sunset maple |
Sun | To 25′ high and 20′ wide | Drought tolerant, very cold hardy, moderate growth rate | |
Amelanchier alnifolia
Western serviceberry |
Sun/part shade | 10′-20′ high and 25′ wide | April – May | Drought tolerant, large white flowers, purple to black berries, rust can be a big problem |
Corylus cornuta
Beaked hazelnut |
Sun/part shade | 20′-30′ high and 15′ wide | April – May | Edible nuts, intolerant of saturated soils, catkins hold through winter |
Crataegus douglasii Black hawthorn |
Sun/part shade | 20′-30′ high and 25′ wide | Spring | Gravelly soils, small white flowers, black berries, 1†spines forms thickets |
Fraxinus oxycarpa
Raywood ash |
Sun | 25′-50′ high and 25′ wide | Spring | Drought tolerant, grows in variety of soil types, can take extreme temperatures will not tolerate constant wind or fog, resists pests and disease |
Rhamnus purshiana
Cascara |
Sun/shade | 20′-40′ high and 25′ wide | Small greenish-yellow flowers, sensitive to air pollution, yellow fall color | |
Salix scouleriana
Scouler willow |
Sun/part shade | 6′-40′ high and 25′ wide | Drought tolerant, do not plant near paved surfaces or underground structures | |
Salix sitchensis
Sitka willow |
Sun/part shade | 3′-26′ high and 25′ wide | Tolerates seasonal flooding, do not plant near paved surfaces or underground structures | |
*Thuja plicata
Western red cedar |
Part shade/shade | 200’+ and 60′ wide | Tolerates seasonal flooding and saturated soils, long lived and prefers shade when young |
Zone 2 Shrubs
Species/Common Name | Exposure | Mature Size | Bloom Time | Comments |
---|---|---|---|---|
Acer circinatum
Vine maple |
Filtered sun/shade | To 25′ | Spring | Tolerant of shade and clay soils, excellent soil binder, beautiful fall color |
Hamamellis intermedia
Diane witchhazel |
Sun/part shade | 10′-20′ high and 10′ wide | January-March | Showy fall color, yellow orange, long lasting, fragrant coppery-red flowers, not drought tolerant, requires watering |
Oemleria cerasiformis
Indian plum/Osoberry |
Sun/part shade | 5′-16′ high | February-March | Prefers shade, tolerates fluctuating water table |
Philadelphus x lemoinei ‘Belle Etoile’
Mock Orange |
Sun/part shade | 5′-6′ high | May-June | Soil and pH adaptable, easily transplanted and established, fragrant, large white flowers, tinged red at base. Variety is hard to find but species is not |
Ribes lacustre
Black swamp gooseberry |
Part shade | 1.5′-3′ high | Reddish flowers in drooping clusters, dark purple berries | |
Rosa nutkana
Nootka rose |
Sun/part shade | 6′-10′ high | April-June | Tolerates inundation and saturated soils, aggressive spreader, fruits persist, less thorny then R. rugosa |
Rosa rugosa
Rugosa rose varieties |
Sun | To 8′ high | Drought resistant, hardy, vigorous and aggressive, highly prickly, fragrant white to purple flowers, fruits persist | |
Rubus parviflorus
Thimbleberry |
Sun/part shade | 4′-10′ high | May-June | White flowers, red berries, will make thickets and spreads easily |
Rubus spectabilis
Salmonberry |
Part sun/shade | 5′-10′ high | February-April | Good soil binder, magenta flowers, yellow/orange fruit, early nectar source for hummingbirds, makes thickets |
Sambucus racemosa
Red elderberry |
Part sun/part shade | To 20′ high | April-May | Small white flowers, bright red berries, vase shaped, pithy stems lead to messy form, prune for tidiness |
Symphoricarpos albus
Snowberry |
Sun/part shade | 2′-6′ high | Excellent soil binder, drought and urban air tolerant, provides good erosion control, spreads well in sun | |
Vaccinium parviolium
Red huckleberry |
Part shade/shade | 4′-10′ high | Prefers loamy, acid soils or rotting wood, tolerant of dry, shady areas, red fruit, trick to transplant, low availability |
Zone 2 Herbaceous
Species/Common Name | Exposure | Mature Size | Bloom Time | Comments |
---|---|---|---|---|
Aquilegia formosa
Western columbine |
Sun/part shade | 1′-3′ high | Spring | Tolerant of seasonal flooding, red and yellow flowers attract hummingbirds and butterflies |
Asarum caudatum
Wild ginger |
Part shade/shade | To 10†high | Mid spring | Heart shaped leaves, reddish brown flowers |
Aster chilensis
Common California aster |
Sun | 1.5′-3′ high | June-September | Moist soils, white to purple flowers |
Aster subspicatus
Douglas aster |
Sun | .5′-2.5′ high | June-September | Moist soils, blue to purple flowers |
Camassia quamash
Common camas |
Sun/part shade | To 2.5′ high | May-June | Lots of watering needed to establish, loose clusters of deep blue flowers |
Camassia leichtilnii
Giant camas |
2′-4′ high | May-June | Need lots of watering to establish, large clusters of white, blue or greenish-yellow flowers | |
Iris douglasiana
Pacific coast iris |
Sun/part shade | 1′-2′ high | Spring | Withstands summer drought and seasonal flooding, white, yellow, blue, reddish-purple flowers, fast growing |
Iris foetidissima
Gladwin iris |
Sun/part shade | 1′-2′ high | May | Well drained soils, pale lilac flower, also called stinking iris |
Juncus tenuis
Slender rush |
Sun | .5′-2.5′ high | Moist soils, yellow flowers | |
Iris siberica
Siberian Iris |
Sun | 1′-2.5′ high | Late spring | Moist soils, deep blue, purple to white flowers |
Tellima grandiflora
Fringecup |
Part sun/shade | 1′-3′ high | March-June | Prefers moist soils, yellowish-green to pink flowers |
Tiarella trifoliate
Foamflower |
Part sun/shade | To 1′ high | Early-mid summer | Moist soils, some drought tolerance after established, can form dense colonies |
Tolmiea menziesii
Piggy-back plant |
Part shade/shade | 1′-2′ high | April-August | Brownish purple flowers, makes and effective ground cover |
Viola species
Violet |
Part shade/shade | .5′-1′ high | Late spring-early summer | Moist soils, yellow to blue flowers
|
Zone 3 Trees
Species/Common Name | Exposure | Mature Size | Bloom Time | Comments | |
---|---|---|---|---|---|
Cornus spp.
Dogwood |
Sun/part shade | 20′-30′ high and 30′ wide | May | Reliable flowering trees with attractive foliage and flowers, may need water in summer | |
Prunus emarginata
Bitter cherry |
Sun/part shade | 20′-50′ high and 20′ wide | May-June | Intolerant of full shade, purple to black cherries, roots spread extensively and tree’s have high mortality rate | |
Prunus virginana
Choke cherry |
3′-25′ high and 15′-20′ wide | Late spring-early summer | Dry or moist soils, deep rooting, attractive white fragrant flowers, good fall color, low availability | ||
*Pseudotsuga menziesii
Douglas fir |
Sun | 100′-250’Â high and 50′-60′ wide | Medium to fast rate of growth, provides a nice canopy but potential will restrict placement | ||
Quercus garryana
Oregon white oak |
Sun | To 75′ | Dry to moist, well drained soils, slow growing, has acorns |
Zone 3 Evergreen Trees
Species/Common Name | Exposure | Mature Size | Bloom Time | Comments | |
---|---|---|---|---|---|
*Arbutus unedo
Strawberry tree |
Sun/part shade | 8′-35′ high and 8′-20′ wide | November-December | Tolerant of extremes, tolerant of urban/industrial pollution, white or greenish white flowers | |
*Calocedrus decurrens
Incense cedar |
Sun | 75′-90′ high and 12′ wide | Tolerant of poor soils, drought tolerant after established, narrow growth habit, slow growing | ||
*Chamaecyparis obtuse
Hinoki false cypress |
Sun/part shade | 40′-50′ high and 25′-30′ wide | Very slow growing, prefers sun but tolerates shade, does not transplant well or do well in alkaline soils | ||
*Pinus mugo
Swiss mountain pine |
Sun/part shade | 15′-20′ high and 25′-30′ wide | Slow growing, broadly spreading, bushy tree, hardy evergreen | ||
*Pinus thunbergiana
Japanese black pine |
Sun | To 100′ high and 40′ wide | Prefers dry to moist soils, hardy, fast growing, low availability |
Zone 3 Shrubs
Species/Common Name | Exposure | Mature Size | Bloom Time | Comments | |
---|---|---|---|---|---|
Holodiscus discolor
Oceanspray |
Sun/part shade | To 15′ high | June-July | Dry to moist soils, drought-tolerant, white to cream flowers, good soil binder | |
Philadelphus lewisii
Mock-orange |
Sun/part shade | 5′-10′ high | June-July | Adapts to a variety of soils, drought tolerant, fragrant flowers | |
*Pinus mugo pumilo
Mugho pine |
Sun | 3′-5′ high and 4′-6′ wide | Adapts to moist soils, slow growing and very hardy | ||
Potentilla fruticosa
Shrubby cinquefoil |
Sun | To 4′ high | May-September | Moist to dry soils, several cultivars available with varying foliage and flower hues | |
Potentilla gracillis
Graceful cinquefoil |
Sun | 1′-2′ high | July | Moist to dry soils, yellow flowers | |
Ribes sanguineum
Red-flowering currant |
Sun/part shade | 8′-12′ high | March-April | Prefers dry soils, drought tolerant, white to deep-red flowers attract hummingbirds, thornless | |
Rosa gymnocarpa
Baldhip rose |
Part shade | To 6′ high | May-July | Dry or moist soils, drought tolerant, small pink to rose flowers |
Zone 3 Evergreen Shrubs
Species/Common Name | Exposure | Mature Size | Bloom Time | Comments | |
---|---|---|---|---|---|
*Abelia x grandiflora
Glossy abelia |
Part sun/part shade | To 8′ high and 5′ wide | Summer | Prefers moist, well drained soils but drought tolerant, white or faint pink flowers | |
*Arbutus unedo ‘Compacta’ Compact strawberry tree |
Sun/part shade | To 10′ high | Fall | Tolerant of poor soils, good in climate extremes, white to greenish white flowers, striking red/orange fruit | |
*Cistus purpureus
Orchid rockrose |
Sun | To 4′ high | June-July | Drought resistant, fast growing, reddish purple flowers | |
*Cistus salviifolius
White rockrose |
Sun | 2-3′ high and 6′ wide | Late spring | Tolerates poor soils, tolerant of windy conditions and drought, white flowers | |
*Escallonia x exoniensis
‘fradesii’ Pink Princess Escallonia |
Sun/part sun | 5′-6′ high | Spring-fall | Drought tolerant when established, pink to rose colored flowers, good hedge or border plant, attracts butterflies. | |
*Osmanthus delavayi
Delavay Osmanthus |
Sun/part shade | 4′-6′ high | March-May | Tolerant of a variety of soils, attractive foliage and clusters of white fragrant flowers, slow growing | |
*Osmanthus x burkwoodii
Burkwood osmanthus |
Sun/part shade | 4′-6′ high | March-April | Drought tolerant once established, masses of small, white fragrant flowers | |
*Rhododendron ‘PJM’
PJM Rhododendron |
Sun/part shade | To 4′ high | Mid-late April | Moist to fairly dry soils, well drained organic soil, lavender to pink flowers | |
*Stranvaesia davidiana
Chinese photinia |
Sun | 6′-20′ high | June | Moist soils, white flowers in clusters, showy red berries, low availability | |
*Stranvaesia davidiana undulata
Prostrate stranvaesia |
Sun | To 5′ high | June | Moist soils, lower growing irregularly shaped shrub, great screening plant. Has very low availability | |
*Vaccinium ovatum
Evergreen huckleberry |
Sun/part shade | 3′-15′ high | March | Moist to slightly dry soils, small pinkish white flowers, edible berries in August |
Zone 3 Evergreen Groundcover
Species/Common Name | Exposure | Mature Size | Bloom Time | Comments | |
---|---|---|---|---|---|
*Arctostaphylos uva-ursi
Kinnikinnick |
Sun/part shade | April-June | Prefers sandy/rocky, well drained soils, flowers pinkish white, bright red berries, slow to establish, plant closely | ||
*Gaultheria shallon
Salal |
Part shade/shade | 3′-7′ high | March-June | White or pinkish flowers, reddish-blue to dark-purple fruit | |
*Fragaria chiloensis
Wild strawberry |
Sun/part shade | 10†high | Spring | Sandy well drained soils, flowers white, aggressive spreader | |
*Helianthemum nummularium
Sunrose |
Sun | To 2′ high and wide | May-July | Will tolerate many soil types, woody perennial, many varieties are available with varying flower colors | |
*Lavandula angustifolia
Lavender |
Sun/part shade | To 1.5′ high | June-August | Adaptable to variety of soils, blue, lavender, pink to white flowers, semi evergreen, aromatic. Does not like PNW wet winters | |
*Mahonia nervosa
Cascade Oregon Grape |
Sun/part shade | To 2′ high | April-June | Dry to moist soils, drought resistant, yellow flowers, blue berries | |
*Mahonia repens
Creeping mahonia |
Sun/part shade | 3′ high | April-June | Dry to moist soils, drought resistant, yellow flowers, blue berries | |
*Penstemon davidsonii
Davidson’s penstemon |
Sun | To 3†high | June-August | Low growing evergreen, prefers well drained soils, drought tolerant, blue to purple flowers. |
Zone 3 Perennials & Ornamental Grasses
Species/Common Name | Exposure | Mature Size | Bloom Time | Comments | |||
---|---|---|---|---|---|---|---|
Achillea millefolium
Western yarrow |
Sun | 4â€-2.5′ high | June-September | Dry to moist, well drained soils, white to pink/reddish flowers | |||
Anaphalis margaritaceae
Pearly everlasting |
Sun/part shade | To 18†high | Drought tolerant perennial, spreads quickly, attracts butterflies | ||||
Bromus carinatus
California brome |
Sun/part shade | 3′-5′ high | Dry to moist soils, tolerates seasonal saturation, low availability | ||||
Carex buchanaii
Leather leaf sedge |
Sun/part shade | 1′-3′ high | Copper-colored foliage, perennial clumping grass, tolerant of many soils | ||||
Carex comans ‘Frosty Curls’
New Zealand hair sedge |
Sun/part shade | 1′-2′ high | June-August | Finely textured and light green, compact, clumping perennial grass, drought tolerant when established | |||
Coreopsis spp.
Tickseed |
Sun | 1′-3′ high | Dry to moist soils, drought tolerant, seeds attract birds, annual and perennial varieties | ||||
Echinacea purpurea
Purple coneflower |
Sun | 4′-5′ high | Prefers well drained soils, hardy perennial, may need water in dry times | ||||
Elymus glaucus
Blue wildrye |
Sun/part shade | 1.5′-5′ high | Dry to moist soils, shade tolerant, rapid developing but short lived (1-3 years) do not use as lawn grass | ||||
Dicentra Formosa
Pacific bleeding heart |
Sun/shade | 6â€-20†high | Early spring-early summer | Moist, rich soils, heart shaped flowers | |||
Erigeron speciosus
Showy fleabane |
Sun/part shade | To 2′ high | Summer | Moist to dry soils, dark violet or lavender blooms, fibrous roots | |||
Festuca ovina ‘Glauca’
Blue fescue |
Sun/part shade | To 10†high | May-June | Blue-green evergreen grass, drought tolerant, shearing will stimulate new growth | |||
Festuca idahoensis
Idaho fexcue |
Sun/part shade | To 1′ high | Bluish-green bunching perennial grass, drought tolerant | ||||
*Fragaria vesca
Wood strawberry |
Part shade | To 10†high | Late spring-early summer | Dry to moist soils, white flowers | |||
Gaultheria shallon
Salal |
Sun/shade | 3′-7′ high | March-June | Dry and moist soils, white or pinkish flowers, reddish-blue to dark-purple fruit | |||
Gaura lindheimeri
Gaura |
Sun | 2.5′-4′ high | Perennial, fairly drought tolerant and adaptable to varying soil types | ||||
Geum macrophyllum
Large-leaved avens |
Sun/part shade | To 3′ high | Spring | Bright yellow flowers, other cultivars available, some may require more water | |||
Geranium maculatum
Spotted geranium |
Sun/shade | To 1.5′ high | July | Moist, well drained soils, low perennial, pale pink, blue to purple flowers, low availability | |||
Geranium sanguineum
Cranesbill |
Sun/part shade | To 1.5′ high | May-August | Moist soils, deep purple, almost crimson flowers | |||
*Helichrysum italicum
Curry plant |
Sun | To 2′ high | Summer | Hardy evergreen perennial, good companion to lavender, bright yellow fragrant flowers, low availability | |||
*Helictotrichon sempervirens
Blue oat grass |
Sun/part shade | 1′-1.5′ high | June-August | Clumping bright blue evergreen grass, bluish white flowers | |||
Hemerocallis fulva
Day lilies |
Sun/part shade | 1′-4′ high | Summer | Easy to grow and tolerant of neglect, hardy perennial, entire plant is edible | |||
Heuchera americana
Coral bells |
Sun/part shade | 1′-2′ high | June-August | Easily transplantable perennial, red, greenish-white flowers, may need supplemental watering in dry season | |||
*Heuchera micrantha
‘Palace Purple’ |
Sun/part shade | 1′-2′ high | June-August | Bronze to purple foliage in shade, small yellowish flowers, evergreen perennial | |||
Lupinus
Lupines |
Sun | 3′-5′ high | March-September | Various native varieties, blue to purple, violet to white flowers | |||
Lupinus bicolor
Two color lupine |
Sun | 4â€-1.5′ high | Spring | Dry gravelly soils, small flowered annual | |||
Lupinus latifolius
Broadleaf lupine |
Sun | To 1′ high | June-August | Dry to moist soils, perennial, bushy herb, bluish flowers, low availability | |||
Lupinus polyphyllus
Large-leafed lupine |
Sun | To 3′ high | Spring-summer | Dry to moist, sandy to gravelly soils, perennial | |||
Mahonia aquifolium
Tall Oregon grape |
Sun/part shade | 6′-10′ high | March-April | Drought resistant evergreen, blue-black fruit, bright yellow flowers, great low screening barrier | |||
Maianthemum dilatatum
False lily-of-the-valley |
Part shade/shade | 3â€-12†high | Spring | Moist soils, small white flowers, light green to red berries | |||
Pennisetum alopecuroides
Fountain Grass |
Sun/part shade | 1′-2′ high | August-September | Tolerant of many soil types, clump forming grasses | |||
Pennisetum orientale
Oriental fountain grass |
Sun/part shade | 1′-3′ high | June-October | Somewhat drought tolerant, small clumping, blooming grass, showy pink flowers | |||
*Penstemon fruticosus
Bush penstemon |
Sun | 8â€-10†high | May | Prefers well drained soils, evergreen perennial, drought tolerant, violet blue flowers 1†long attract hummingbirds | |||
*Polystichum munitum
Swordfern |
Part shade/deep shade | 2′-4′ high | Prefers moist, rich soil conditions but drought tolerant, large evergreen fern | ||||
Rudbeckia hirta
Black-eyed susan |
Sun/part shade | 3′-4′ high | Summer | Moist to dry soils, showy flowers, hardy and easy to grow | |||
Smilacina racemosas
False solomons seal |
Part sun/shade | 1′-3′ high | April-May | Moist soils, creamy white flowers, red berries | |||
Solidago Canadensis
Canadian goldenrod |
Sun/part shade | 1′-2′ high | Late summer-early fall | Dry to moist soils, yellow flowers |