kentucky residential rain gardens

8/3/2019 Kentucky Residential Rain Gardens

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Residential Rain Gardens

Rick Durham

Consumer Horticulture Extension SpecialistUniversity of Kentucky


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Rain garden strategically located low areaplanted with native vegetation that interceptsrunoff and allows it to infiltrate the soil.


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Photo Copyright 1999, Center for Watershed Protection

Why Should We Consider Rain Gardens?


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Run Off

Typical run off from a city block is 9Xgreater than a wooded area of similar

size due to pavement -substantially, but not completely

Rain gardens promote 30% moreinfiltration than lawns


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Flooding from 3 Rainfall


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Rain Garden?No! Erosion and nutrient run off upstream results insiltation downstream.


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Rain Gardens

Increase the amount of water thatinfiltrates the soil to recharges aquifers

Help protect community from flooding

Help protect streams and lakes frompollutants carried in run off

Enhance neighborhood beauty Provide wildlife habitat


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Rain Gardens Can Be Beautiful


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Excavation of an infiltration trench


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Completed Infiltration Trench


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Overflow to Storm Drain


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Stormwater Runoff Solutions begin byreducing the amount of impermeable

surfaces.


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Grass Pave


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Single FamilyResidence or Commercial Property


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Ok, Lets Now Take a Lookat Rain Gardens


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Getting Started

How Big does it need to be? Where do I need to locate it?

Soil Considerations? What Plants should we use?


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How big do I make my raingarden ?

Design it to handle a 1.25 inch rain event

(this captures 80% of rainfall events) Square footage x 1.25 in. (or .104 ft) = X cu ft of water


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60 feet30feet

60 x 30 = 1800 sq. ft.

1800 sq. ft. x .104 ft. of rain (1.25 in rain)=

187 cu. Ft. of water

Just for Fun

187 cu. ft. of water x 7.48 = 1398 gallons


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187 cu. Ft. of water

10 x 12 x 1.5 feet deep = 180 cu. Ft.


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Size of Rain Garden

Rain Gardens can be of any size or shape

Sandy soil, garden should be 20-30% of

Heavy clay soils, garden should be 50-60% the size of the drain area

Most residential rain gardens will be100-300 sq. ft.


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Where does it need to be?

Locate the rain garden down slope from anybuildings

Away from large trees (easier digging) In areas that take advanta e of natural slo e. Consider the size and placement in the

landscape design. It may be easier to createtwo separate rain gardens.


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Excavating

For large projects it may be easier to hire alandscaper.

For smaller projects use the excavated soil

to build a berm on the downhill side of the. Use a rope or water hose to layout the edge

of the garden, use stakes and string to level.

For deep gardens set aside the top 4-6inches of soil (topsoil), excavate the holethen use the top soil to backfill the plantingarea.


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Soil Considerations

Do a perk test. Dig a hole 8 inches deep and fill withwater. If it takes more than 24 hours to drain thenthe soil needs to be amended.

On poorly drained soil excavate 10-12 inches of soil

from hole, mix 3-6 inches of coarse sand or smallravel with excavated soil and re lace into raingarden.

Bring 2 cups of soil to Extension Office for soil testAdd lime and fertilizer according to soil test results,3-6 inches of organic matter then till to a depth of 6

inches. Rain garden soil mix = 50-60% sand, 20-30% top soil,20-30% compost (Rain Gardens of WesternMichigan)


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What about mosquitoes?

Life cycle requires 7-14 days from eggto adult

Require standing water during juvenile

Most rain gardens will drain within 3-4days, usually sooner

A properly designed rain garden will notbreed mosquitoes!


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Now the fun part Picking the

plants Determine sun exposure

Full sun = 6 or more hours of direct sun Part Sun to Part Shade=

less than 6 hours of direct sun Shade = virtually no direct sun - problems

Dont forget specific site problems Plants will need to be watered until established Weed management strategy needed for first year

or so Choose native were possible. Drought tolerant,

deep rooted, deer resistant?


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Trees

Deciduous / Evergreen

Plant as Specimens or in Groups Consider Bark / Shape / Flowering Provide Habitats for Birds


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Trees for Rain Gardens

Sweetbay Magnolia Winter King

Hawthorn Hackberr

Red Maple River Birch Black Gum

Fringetree Ginko

Willow Oak Sycamore


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River Birch

Distinguished bybark

50' X 50' mature size Drou ht tolerance Multi-stemmed


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Baldcypress Drought

Tolerance Deciduous 60' x 25' Plant as

Specimen or inGroups


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Red Maple

40'-60' x 40'-60'

Droughto erance Excellent Fall

Color


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Ginkgo

25'-50' X 20'-40'

Pest Free / Resistanceo amage Tolerates Most Soil

Conditions


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Ginkgo - Fruit / Leaf

Fan Shaped

Leaf Undesirable

Fruit


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Black Gum

Nyssa sylvatica 60-80 feet Deciduous


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Willow Oak

Quercus phellos 40-60 ft. Hightower


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Sweetbay Magnolia

Magnolia virginiana 20-30 ft. Evergreen


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Winter King Hawthorn

Crategus virdis'Winter King

Slow growth 15-20 ft. Deciduous Fall/winter berries


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Hackberry

Celtis occidentalis 80 ft. Deciduous

.


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Fringetree

Chionanthusvirginicus

Small understoryree

deciduous


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Shrubs for Rain Gardens

Arrowwood Buttonbush Summersweet

Clethra

AmericanBeautyberry

BottlebrushBuckeye

Wax Myrtle Inkberry Oakleaf Hydrangea

Sweetspire


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Inkberry

DroughtTolerance

Withstands Heavy

Pruning Adapted to

Various SoilTypes


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Arrow wood

Viburnumdentatum

8 ft tall x 6 ft. Fruit eaten by

birds Fall color red to

reddish purple


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Bottlebrush Buckeye

Aesculus parviflora 8-15 ft. Deciduous

stalk in June


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Oakleaf Hydrangea

Hydrangeaquercifolia

6 feet Deciduous Great fall color


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Sweetspire

Itea 4-5 feet tall and wide Great burgundy fall

color May-June white

fragrant flowersresembling fluffycaterpillars


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Buttonbush

Cephalanthusoccidentalis

18 ft. Bees and

butterflies Fragrant

Dried flowersoften remainthrough winter


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Sweet Pepperbush

(Summer Sweet Clethra) Clethra alnifolia Blooms June-

Jul Drought Tolerant Yellow Fall Color

ExcellentFragrance 10 ft.


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American Beautyberry

6' x 6' Drought

Tolerance Cut Back Each

Year Berries for

Wildlife


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Herbaceous Plants for Rain

Gardens Swamp Milkweed Cinnamon Fern Canna Lilies

Asters Blackeyed Susan Lobelia

Rushes Liriope/Mondograss

Ironweed Joe Pye Weed St. Johns Wort


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Asters

Aster novae-angliaeNew England Aster

Color:purple

Late summer/fallflowering


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Blackeyed Susan

Rudbeckia 'Indian Summer Goldstrum

flowering

Foliage 8-12 inches

Flowers up to 2 feet


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Lobelia cardinalis Cardinal Flower

Red flowers in later summer and fall

Cardinal Flower

2-4 feet tall Few pests


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Goldenrod

SolidagoGoldenrod

Height: cultivar dependent, 3-6 feet

Late summer/fallflowering

Not considered acontributor to hayfever


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St. Johns Wort

Hypericum spp. 200 species

Ground cover tomedium shrub


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Swamp Milkweed

Asclepias incarnata Summer flowers Butterflies

aphids


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Ironweed

Vernonianoveboracensis

Flowers mid to late

summer Height to 6 feet Butterflies


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Liriope

Great Border Ground Cover

Grows in Moistreas Easy to Grow Increase by

Division


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Cinnamon Fern

Osmundacinnamomea

Deciduous

2-5 feet ht.


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Joe Pye Weed

Eupatorium Late Summer

Flowers Tall Robust Plant Flower heads

attractive after plant dries in fall


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Miscanthus sinensis Silver Grass

Grasses

Pennisetum alopecuroides Fountain Grass

Phalaris arundinaceae Ribbon Grass

Festuca cinerea Silver Fescue


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Rushes and Sedges

Juncus and Carex Grass-like Tolerant of wet sites

well


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Planting Trees and Shrubs

When planting individual plants, dig the hole2-times wider than the root ball.When planting a group of plants, cultivate

the planting area to a 12-inch depth. Do not add amendments to individualplanting holes. Instead, incorporateamendments uniformly into the top 12

inches of the soil.Remove the wire or cord from around thestem of B&B plants.


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Planting Trees and Shrubs

Slice or break apart the root ball of pot-bound container-grown plants.Install guy wires on trees, if necessary,

but remove them after establishment.A water saucer may be used to helpdirect water to the roots, but it is onlytemporary.Mulch.Water to settle soil.


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If a water saucer is used, rake it outward andaway from the planting hole. Smooth saucer 2 to 3months after planting to keep it from eroding over

the roots


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Planting herbaceous plants

Plant in waves rather than as single plants Consider height and period/color of bloom Plant no deeper than previously growing

Provide 1 water per week until established Prune back vegetation prior to regrowth in

spring


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Mulch

A minimum of 2 needed, not more than 4 Keeps weeds down

Acts as sponge to capture heavy metals,oils and grease Holds moisture Maintains even temperature

Shredded hardwood mulch or pine strawrecommended


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Pondering Points

The planting plan design shouldinclude species that tolerate extremes.

a natural wild condition.

Native plants are best adapted to localclimate and once established aregenerally low maintenance.


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Pondering Points

(continued) When planted with native species rain

gardens can have additional value as a.

Shrub, trees, and ground covers absorbup to 14 times more rainwater than a

grass lawn.


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Maintenance?

No special maintenance required onceestablished

ou ne per o c an scap ngmaintenance

Weeding

Irrigation Pruning/vegetation removal


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For more information: Rain Gardens of Western Michigan

http://www.raingardens.org/Index.php Rain Gardens Gardening with water quality in

mind. http://www.mninter.net/~stack/rain/ Rain ardens infiltratin Wisconsin

http://www.dnr.state.wi.us/org/water/wm/nps/rg/

Credits: Residential Rain Gardens. Todd Hurt, UGA/

Cherokee Co. Extension. Milti-state Master Gardener Educator Training: Landscape Water QualityWorkshop, Griffin, GA. 2004.

kentucky residential rain gardens

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