the rain garden manual for homeowners

8/14/2019 The Rain Garden Manual for Homeowners

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A how-to manual

for homeowners


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Homeowners in many parts of the country are catching on to rain gardens land-scaped areas planted to wild owers and other native vegetation that soak up rain water,mainly from the roof of a house or other building. The rain garden lls with a few inchesof water after a storm and the water slowly lters into the ground rather than running offto a storm drain. Compared to a conventional patch of lawn, a rain garden allows about

30% more water to soak into the ground.

Why are rain gardens important? As cities and suburbs grow and replace forests andagricultural land, increased stormwater runoff from impervious surfaces becomes aproblem. Stormwater runoff from developed areas increases ooding; carries pollutantsfrom streets, parking lots and even lawns into local streams and lakes; and leads to costlymunicipal improvements in stormwater treatment structures.

By reducing stormwater runoff, rain gardens can be a valuable part of changing these

trends. While an individual rain garden may seem like a small thing, collectively theyproduce substantial neighborhood and community environmental benets. Rain gardenswork for us in several ways:

g Increasing the amount of water that lters into the ground, whichrecharges local and regional aquifers;

g Helping protect communities from ooding and drainage problems;

g Helping protect streams and lakes from pollutants carried byurban stormwater lawn fertilizers and pesticides, oil andother uids that leak from cars, and numerousharmful substances that wash off roofs andpaved areas;

g Enhancing the beauty of yards and neighborhoods;

g Providing valuable habitat for birds, butteriesand many benecial insects.

Your personal contribution to cleaner water

2


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Frequently asked questionsDoes a rain garden form a pond?

No. The rain water will soak in so the rain garden is drybetween rainfalls. (Note: some rain gardens can bedesigned to include a permanent pond, but that type ofrain garden is not addressed in this publication).

Are they a breeding ground for mosquitoes?

No. Mosquitoes need 7 to 12 days to lay and hatch eggs,and standing water in the rain garden will last for a fewhours after most storms. Mosquitoes are more likely to lay

eggs in bird baths, storm sewers, and lawns than in asunny rain garden. Also rain gardens attract dragonies,which eat mosquitoes!

Do they require a lot of maintenance?

Rain gardens can be maintained with little effort after theplants are established. Some weeding and watering will beneeded in the rst two years, and perhaps some thinning

in later years as the plants mature.

Is a rain garden expensive?

It doesnt have to be. A family and afew friends can provide the labor. Themain cost will be purchasing the plants,and even this cost can be minimized byusing some native plants that might

already exist in the yard or in aneighbors yard.

Who should use thismanual?This manual provideshomeowners and landscapeprofessionals with theinformation needed todesign and build raingardens on residential lots.Guidelines presented in thismanual can also be used totreat roof runoff at com-mercial and institutionalsites. However, the manualshould not be used todesign rain gardens forparking lots, busy streetsand other heavily usedpaved areas wherestormwater would requirepretreatment beforeentering a rain garden.

Rain Gardens A how-to manual for homeowners 3


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Sizing and Siting the Rain Garden

This section of the manual covers rain gar-den basics where to put the rain garden,how big to make it, how deep to dig it, andwhat kind of soils and slope are best. Followingthe instructions in this section is the best wayto ensure a successful rain garden project.

If you already know the size you want your raingarden to be, then skip ahead to the sectionabout building the rain garden. However, take time read the pointers about location, anddo nd the slope of the lawn. If the location has a slope more than about 12%, its best topick a different location because of the effort it will take to create a level rain garden.

Where should the rain garden go?Home rain gardens can be in one of two places near the house to catch only roof runoff or farther out onthe lawn to collect water from the lawn and roof. (Figure 1 shows the possible locations on a residential lot.)To help decide where to put a rain garden, consider these points:

The rain garden should be at least 10 feet from the house so inltrating water doesntseep into the foundation.

Do not place the rain garden directly over a septic system.

It may be tempting to put the rain garden in a part of the yard where water alreadyponds. Dont! The goal of a rain garden is to encourage inltration, and your yards wetpatches show where inltration is slow.

It is better to build the rain garden in full or partial sun, not directly under a big tree.

Putting the rain garden in a atter part of the yard will make digging much easier.For example, a rain garden 10 feet wide on a 10% slope must be 12 inches deep to belevel, unless you import topsoil or use cut and ll.

4

Step 1

An extension of PVC pipe helps direct downspout waterto this rain garden.


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not within 10'of foundation

> 30'from

down spout

street

roof and lawndrainage

area to backrain garden

roof drainagearea to frontrain garden

rain gardenlength

raingardenwidth

r a i n g a r d e n

w i d t h

close todown spout

r a i n g a r d e n

l e n g t h

When considering placement of your raingarden, design with the end in mind.Carefully consider how the rain garden can

be integrated into existing and futurelandscaping. Also, pay attention to viewsfrom inside the house as well as those


throughout the landscape. Determine howfar or how close you want your rain gardento outdoor gathering spaces or other play

areas. Why not locate it near a patio whereyou can take advantage of the colors andfragrances for hours on end!

Figure 1 A rain garden canbe built in the front or back yard. Pick a pleasing shapefor the rain garden. Crescent,kidney, and teardrop shapes

seem to work well.

Consider your overall landscape


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How big should the rain garden be?The surface area of the rain garden can be almost any size, but time and cost will always be important con-siderations in sizing decisions. Any reasonably sized rain garden will provide some stormwater runoff control.A typical residential rain garden ranges from 100 to 300 square feet. Rain gardens can be smaller than 100square feet, but very small gardens have little plant variety. If a rain garden is larger than 300 square feet ittakes a lot more time to dig, is more difficult to make level, and could be hard on your budget.

The size of the rain garden will depend on

how deep the garden will be,

what type of soils the garden will be planted in, and

how much roof and/or lawn will drain to the garden.

This information, along with the sizing factor from the tables onpage 9, will determine the surface area of the rain garden.

> 10'from

foundation

< 12%slope

bermberm

street

> 30'from

down spout

closeto

down

spout

Guidelines are not rulesThe sizing guidelinesdescribed in this manual are

based on a goal of controlling100% of the runoff for theaverage rainfall year whilekeeping the size of the raingarden reasonable. Establish-ing a 100% runoff goal helpscompensate for some of theerrors that creep into thedesign and construction ofany rain garden.

If you follow the guidelines inthe manual and decide thecalculated surface area is justtoo large for your goals, it isperfectly acceptable to makethe rain garden smaller. Therain garden can be up to 30%smaller and still control almost90% of the annual runoff. Onthe other hand, it is ne tomake the rain garden bigger

than the guidelines indicate.

Figure 2 Rain gardens shouldbe located at least 10 feet fromthe house, on a gentle slopethat catches downspout water.

Digging with a rented backhoe.


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How Deep Should the Rain Garden Be?A typical rain garden is between four and eight inches deep. A rain garden more than eight inches deepmight pond water too long, look like a hole in the ground, and present a tripping hazard for somebodystepping into it. A rain garden much less than four inches deep will need an excessive amount of surfacearea to provide enough water storage to inltrate the larger storms.

No matter what the depth of

the rain garden, the goal is tokeep the garden level. Digginga very shallow rain garden on asteep lawn will require bringingin extra topsoil to bring thedownslope part of the gardenup to the same height as theup-slope part of the garden. Asthe slope gets steeper, it is easi-er to dig the rain garden a littledeeper to make it level.

The slope of the lawn should determine the depth of the rain garden. Find the slope of your lawn byfollowing these steps. (Figure 3 shows how the stakes and string should look.)

1. Pound one stake in at the uphill end of your rain garden site and pound the other stakein at the downhill end. The stakes should be about 15 feet apart.

2. Tie a string to the bottom of the uphill stake and run the string to the downhill stake.

3. Using a string level or the carpenters level, make the string horizontal and tie the stringto the downhill stake at that height.

4. Measure the width (in inches) between the two stakes.

5. Now measure the height (in inches) on the downhill stake between the ground and string.

6. Divide the height by the width and multiply the result by 100 to nd the lawns percentslope. If the slope is more than 12%, its best to nd another site or talk to a professionallandscaper.

Using the slope of the lawn, select the depth of the rain garden from the following options:

If the slope is less than 4%, it is easiest to build a 3 to 5-inch deep rain garden.

If the slope is between 5 and 7%, it is easiest to build one 6 to 7 inches deep.

If the slope is between 8 and 12%, it is easiest to build one about 8 inches deep.

EXAMPLE

Todd measures the length of the string between the stakes; it is 180 inches long. The heightis 9 inches. He divides the height by the width to nd his lawns percent slope.

With a 5% slope, Todd should build a 6 inch deep rain garden.

heightx 100 =% slopewidth

9 inchesx 100 =5% slope180 inches

downhillstake

height

the string must be leveluphillstake

width

Figure 3 The string should be tied tothe base of the uphill stake, then tied tothe downhill stake at the same level.


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Rain gardens more than 30 feet from the downspout

1. If there is a signicant area of lawn uphill that will also drain to the rain garden, addthis lawn area to the roof drainage area. First nd the roof drainage area using the stepsabove for a rain garden less than 30 from the downspout.

2. Next nd the area of the lawn that will drain to the rain garden. Stand where your raingarden will be and look up toward the house. Identify the part of the lawn sloping intothe rain garden.

3. Measure the length and width of the uphill lawn, and multiply them to nd the lawn area.

4. Add the lawn area to the roof drainage area to nd the total drainage area.

8

How big is the area draining to the rain garden?The next step in choosing your rain garden size is to nd the area that will drain to the rain garden. As thesize of the drainage area increases so should the size of the rain garden. There is some guesswork in deter-mining the size of a drainage area, especially if a large part of the lawn is up-slope from the proposed gardensite. Use the suggestions below to estimate the drainage area without spending a lot of time.

Rain gardens less than 30 feet from the downspout

1. In this case, where the rain garden is close to the house, almost all water will come from

the roof downspout. Walk around the house and estimate what percent of the roof feedsto that downspout. Many houses have four downspouts, each taking about 25% of theroofs runoff.

2. Next nd your homes footprint, the area of the rst oor. If you dont already know it,use a tape measure to nd your houses length and width. Multiply the two together tond the approximate area of your roof.

3. Finally, multiply the roof area by the percent of the roof that feeds to the rain gardendownspout. This is the roof drainage area.

What type of soils are on the rain garden site?After choosing a rain garden depth, identify the lawns soil type as sandy, silty, or clayey. Sandy soils havethe fastest inltration; clayey soils have the slowest. Since clayey soils take longer to absorb water, raingardens in clayey soil must be bigger than rain gardens in sandy or silty soil. If the soil feels very gritty andcoarse, you probably have sandy soil. If your soil is smooth but not sticky, you have silty soil. If it is verysticky and clumpy, you probably have clayey soil.

EXAMPLE

Todds house is 60 feet by 40 feet, so the roof area is 2400 square feet. He estimates thatthe downspout collects water from 25% of the roof, so he multiplies 2400 by 0.25 to get adownspout drainage area of 600 square feet.

Roof Area: 60 ft by 40 ft = 2400 square ft.

Drainage Area: 2400 square ft. x 0.25 = 600 square ft.

If the rain gardenis far from thehouse, and youdont want a swaleor downspoutcutting across the

lawn, run a PVCpipe undergroundfrom the down-spout to the raingarden. In thiscase do calculationsas for a raingarden less than30 feet from thehouse.


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Using the Rain Garden Size FactorsHaving estimated the drainage area, soil type, and depth for your rain garden, use Table 1 or Table 2 todetermine the rain gardens surface area. Use Table 1 if the rain garden is less than 30 feet from the down-spout, and use Table 2 if it is more than 30 feet from the downspout.

Table 1 Rain gardens less than 30 feetfrom downspout.

3-5 in. 6-7 in. 8 in.deep deep deep

Sandy soil 0.19 0.15 0.08

Silty soil 0.34 0.25 0.16

Clayey soil 0.43 0.32 0.20

EXAMPLE

Todds rain garden is less than 30 feet from the downspout, and his lawn has a 5% slope, sohe will have a 6-inch deep rain garden. His lawn is silty, so Table 1 recommends a size factorof 0.25. He multiplies the downspout drainage area, 600 square feet, by 0.25 to nd therecommended rain garden area, 150 square feet.

600 square ft. by 0.25 = 150 square ft.

1. Find the size factor for the soil type and rain garden depth.

2. Multiply the size factor by the drainage area. This number is the recommended raingarden area.

3. If the recommended rain garden area is much more than 300 square feet, divide it into

smaller rain gardens.

Table 2 Rain gardens more than 30 feetfrom downspout.

Size Factor, for all depths

Sandy soil 0.03

Silty soil 0.06

Clayey soil 0.10

Simple soil testsTwo small tests can ensure your soil can handle a rain garden:

Dig a hole about 6 inches deep where the raingarden is to go and ll the hole with water. Ifthe water takes more than 24 hours to soak in,the soil is not suitable for a rain garden.

Take a handful of soil and dampen it with afew drops of water. After kneading the soil in your ngers,

squeeze the soil into a ball. If it remains in a ball, then work the soil between your forenger and thumb, squeezing itupward into a ribbon of uniform thickness. Allow the ribbonto emerge and extend over the forenger until it breaksfrom its own weight. If the soil forms a ribbon more thanan inch long before it breaks, and it also feels more smooththan gritty, the soil is not suitable for a rain garden.

The map is a starting point for assessing what type of soils you might nd in your yard. However, the soil on asmall plot of a yard can be very different from the soils indicated on the map. Use the simple soil test describedhere for a more accurate representation of the soils in the possible rain garden location. More information aboutsampling and testing lawn and garden soils can be obtained at county UW-Extension offices.


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How long and how wide should therain garden be?Before building the rain garden, think about how it will catchwater. Runoff will ow out of a downspout and should spreadevenly across the entire length of the rain garden. The raingarden must be as level as possible so water doesnt pool atone end and spill over before it has a chance to inltrate.

The longer side of the rain garden should face upslope; that is, the length of the rain garden should beperpendicular to the slope and the downspout. This way the garden catches as much water as possible.However, the rain garden should still be wide enough for the water to spread evenly over the whole bottomand to provide the space to plant a variety of plants. A good rule of thumb is that the rain garden should beabout twice as long (perpendicular to the slope) as it is wide.

When choosing the width of the garden, think about the slope of the lawn. Wide rain gardens and raingardens on steep slopes will need to be dug very deep at one end in order to be level. If the rain garden istoo wide, it may be necessary to bring in additional soil to ll up the downhill half. Experience shows thatmaking a rain garden about 10 feet wide is a good compromise between the effect of slope and how deepthe rain garden should be. A rain garden should have a maximum width of about 15 feet, especially forlawns with more than about an 8 percent slope.

To determine the length of the rain garden:

1. Pick the best rain garden width for your lawn and landscaping.

2. Divide the size of your rain garden by the width to nd your rain gardens length.

10

Choose a size that is bestfor your yardRemember that these are onlyguidelines. The size of therain garden also depends onhow much money you want tospend, how much room youhave in your yard, and howmuch runoff you want to con-trol. Again, you can reducethe size of your rain gardenby as much as 30% and stillcontrol almost 90% of therunoff. If the sizing table sug-gests that the rain garden be200 square feet, but there isonly enough room for a140-square-foot rain garden,thats ne. A smaller rain gar-den will usually work to con-trol most stormwater runoff,although some bigger stormsmight over-top the berm.

EXAMPLE

Todd wants a 10-foot wide rain garden, so he divides 150 by 10 to nd the rain gardenlength, 15 feet.

rain garden area= length

width150 ft 2

= 15 ft10 ft

Runoff ows into a new rain garden (shown before plants are fully grown).


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A noteon toolsThe followingtools will help inbuilding the raingarden. Some ofthe tools areoptional.

Tape measure

Shovels

Rakes

Trowels

Carpenterslevel

Wood stakes,at least 2 ftlong

String

2x4 board, atleast 6 ft long(optional)

Small backho

with cater-pillar treads(optional)

Building the Rain Garden

Now that the size and place for the rain garden are set, itstime to get a shovel and start digging. Working alone, it will takeabout six hours to dig an average-size rain garden. If friends help itwill go much faster, possibly only an hour or two.

Step 2

f you are building therain garden into anexisting lawn, diggingtime can be reducedby killing the grassrst. A chemical suchas Round-Up can be

used, but a moreenvironmentallyfriendly approach isto place black plasticover the lawn untilthe grass dies. Also,the best time to buildthe rain garden is inthe spring. It will beeasier to dig, and the

plants are more likelyto thrive.

Before you start digging, callDiggers Hotline at 1-800-242-8511.


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Digging the rain gardenWhile digging the rain garden to the correct depth, heap the soil around the edgewhere the berm will be. (The berm is a low wall around three sides of the rain gardenthat holds the water in during a storm.) On a steeper lawn the lower part of the raingarden can be lled in with soil from the uphill half, and extra soil might need to bebrought in for the berm.

Start by laying string around the perimeter of your rain garden. Remember that the

berm will go outside the string. Next, put stakes along the uphill and downhill sides,lining them up so that each uphill stake has a stake directly downhill. Place one stakeevery 5 feet along the length of the rain garden.

Start at one end of the rain garden and tie a string to the uphill stake at ground level.Tie it to the stake directly downhill so that the string is level. Work in 5-foot-wide sections,with only one string at a time. Otherwise the strings will become an obstacle.

Start digging at the uphill side of the string. Measure down from the string and dig untilyou reach the depth you want the rain garden to be. If the rain garden will be four inchesdeep, then dig four inches down from the string. Figure 4 shows how.

If the lawn is almost at, you will be digging at the same depth throughout the raingarden and using the soil for the berm. If the lawn is steeper, the high end of the raingarden will need to be dug out noticeably more than the low end, and some of the soilfrom the upper end can be used in the lower end to make the rain garden level.Continue digging and lling one section at a time across the length of your rain gardenuntil it is as level as possible.

In any garden, compost will help the plants become established and now is the time tomix in compost if needed. Using a roto-tiller can make mixing much easier, but isntnecessary. If you do add compost, dig the rain garden a bit deeper. To add two inchesof compost, dig the rain garden one to two inches deeper than planned.

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Levelingthe raingardenOne way to check he level of the rain

garden is to justeyeball it. To do it

more accurately fol-ow these steps:

When the wholearea has beendug out to aboutthe right depth,lay the 2x4 boardin the rain gardenwith the carpen-ters level sittingon it. Find thespots that arentat. Fill in the low

places and digout the highplaces.

Move the boardto different placesand differentdirections, llingand digging asnecessary to makethe surface level.

When the raingarden is as levelas you can get it,rake the soilsmooth.

The perimeter of a rain garden is dened with string before digging.


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6"

10'

downhillstake string

startdigging

here

uphillstake

5% slope

string

base of raingarden

uphillstake

downhillstake

old lawnsurface

berm

10'

6"

8"


startdigging

here

uphillstake

10% slope

10'

8"

12"

4"


uphillstake

berm

old lawn

surface

Figure 4 Where to dig and where to put the soil youve dug.

a. Between 3% and 8% slope lawn

b. Greater than 8% slope lawn

BeforeDigging

AfterDigging

BeforeDigging

AfterDigging


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Figure 5 The top of the downhill part of the bermshould come up to the same elevation as the entryto the rain garden at the uphill end.

Making the BermWater owing intro the rain garden will naturally try torun off the downhill edge. A berm is needed to keepthe water in the garden, The berm is a wall across thebottom and up the sides of the rain garden. The berm will need to be highest at the downhill side. Up thesides of the rain garden, the berm will become lower and gradually taper off by the time it reaches the topof the rain garden. Figure 5 shows how the berm should look.

On a at slope there should be plenty of soil from digging out the rain garden to use for a berm. On asteeper slope, most of the soil from the uphill part of the rain garden was probably used to ll in the down-hill half, and soil will have to be brought in from somewhere else. After shaping the berm into a smoothridge about a foot across, stomp on it. It is very important to have a well-compacted berm, so stomp hard.

The berm should have very gently sloping sides; this helps smoothly integrate the rain garden with thesurrounding lawn and also makes the berm less susceptible to erosion.

To prevent erosion, cover the berm with mulch or plant grass. Use straw or erosion-control mat to protectthe berm from erosion while the grass is taking root.

If you dont want to plant grass or mulch over the outside of the berm, you can also plant dry-tolerantprairie species. Some potential berm species are prairie dropseed, little bluestem, prairie smoke, blue-eyedgrass, prairie phlox, and shooting star.

Note: If the downspout is a few feet from the entry to the rain garden, make sure the water runs into thegarden by either digging a shallow grass swale or attaching an extension to the downspout.

On a gentle slope, soil from digging out the gardencan be used to create the berm. This rain garden is4 inches deep.

berm

downspout

uphill uphill

downh


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Tips for designing an attractive rain gardenWhile rain gardens are a highly functional way to help protect water quality, they are alsogardens and should be an attractive part of your yard and neighborhood. Think of therain garden in the context of your homes overall landscape design. Here are a few tips:

When choosing native plants for the garden, it is important to consider the height of eachplant, bloom time and color, and its overall texture. Use plants that bloom at differenttimes to create a long owering season. Mix heights, shapes, and textures to give thegarden depth and dimension. This will keep the rain garden looking interesting even whenfew wildowers are in bloom.

When laying plants out, randomly clump individual species in groups of 3 to 7 plants toprovide a bolder statement of color. Make sure to repeat these individual groupings to

create repetition and cohesion in a planting. This will provide a more traditional formallook to the planting.

Try incorporating a diverse mixture of sedges, rushes, and grasses with your oweringspecies (forbs). This creates necessary root competition that will allow plants to followtheir normal growth patterns and not outgrow or out-compete other species. In naturalareas, a diversity of plant types not only adds beauty but also create a thick undergroundroot matrix that keeps the entire plant community in balance. In fact, 80% of the plantmass in native prairie communities is underground. Once the rain garden has matured and

your sedges, rushes and grasses have established a deep, thick root system, there will beless change in species location from year to year, and weeds will naturally decline.

Finally, consider enhancing the rain garden by using local or existing stone, ornamentalfences, trails, garden benches, or additional wildower plantings. This will help give thenew garden an intentional and cohesive look and provide a feeling of neatness that theneighbors will appreciate.


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Planting the rain garden is the fun part! A number of plantingdesigns and lists of suggested plants are included at the end of thispublication. Use these for ideas, but dont be afraid to be creative theres no single best way to plant a rain garden. Anyone who hasever done any gardening will have no problem planting arain garden, but a few basic reminders are listed below.

Planting the rain gardenSelect plants that have a well established root system. Usually oneor two-year-old plants will have root systems that are beginning tocircle or get matted. (Note: use only nursery-propagated plants; donot collect plants from the wild).

Make sure to have at least a rough plan for which plants will beplanted where. Lay out the plants as planned one foot apart in a grid

pattern, keeping them in containers if possible until they are actuallyplanted to prevent drying out before they get in the ground.

Dig each hole twice as wide as the plant plug and deep enoughto keep the crown of the young plant level with the existing grade(just as it was growing in the cell pack or container). Make sure thecrown is level and then ll the hole and rmly tamp around theroots to avoid air pockets.

Apply double-shredded mulch evenly over the bed approximately twoinches thick, but avoid burying the crowns of the new transplants.Mulching is usually not necessary after the second growing season

unless the mulched look is desired.Stick plant labels next to each individual grouping. This will helpidentify the young native plants from non-desirable species (weeds)as you weed the garden.

As a general rule plants need one inch of water per week. Waterimmediately after planting and continue to water twice a week(unless rain does the job) until the plugs are established. You shouldnot have to water your rain garden once the plants are established.Plugs can be planted anytime during the growing season as long asthey get adequate water.

Planting and Maintaining

the Rain Garden

Step 3

Fire safetyMake sure burning is allowedin your locale. If so, be sure tonotify the local re departmentand obtain a burn permit ifneeded. Its also wise not tomention neighborly to makesure the neighbors know thatyoure burning and that allsafety precautions are beingtaken. Basic re precautionsinclude:

Make sure there is are-break (non-burn-able area, such as turf-grass) at least 10-feetwide surrounding thearea to be burned.

Never burn onwindy days.

Never leave anactively burning reunattended.

Keep a garden hosehandy in case re strayswhere it is not wanted.Also have a metal leafrake in hand to beatout ames that creepbeyond the burn zone.


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Maintaining the rain gardenWeeding will be needed the rst couple of years. Remove byhand only those plants you are certain are weeds. Try to get outall the roots of the weedy plants. Weeds may not be a problem inthe second season, depending on the variety and tenacity ofweeds present. In the third year and beyond, the native grasses,sedges, rushes, and wildowers will begin to mature and willout-compete the weeds. Weeding isolated patches might still beneeded on occasion.

After each growing season, the stems and seedheads can be leftfor winter interest, wildlife cover and bird food. Once springarrives and new growth is 4-6-inches tall, cut all tattered plantsback. If the growth is really thick, hand-cut the largest plants andthen use a string trimmer to mow the planting back to a height ofsix to eight inches. Dead plant material can also be removed witha string trimmer or weed whacker (scythe) and composted or dis-posed of as appropriate.

The best way to knock back weeds and stimulate native plantgrowth is to burn off the dead plant material in the rain garden.

However, burning is banned in most municipalities. Anotheroption is to mow the dead plant material. If the mowing deck ofyour lawn mower can be raised to a height of six inches or so, goahead and simply mow your rain garden. Then, rake up andcompost or properly dispose of the dead plant material.

If the mower deck wont raise that high, use a string trimmer orweed-eater to cut the stems at a height of 6-8 inches. On thickerstems, such as cup plant, goldenrods and some asters, a stringtrimmer may not be strong enough. For these, use hand clippersor pruning shears to cut the individual stems.

What does a raingarden cost?The cost of a rain garden will varydepending on who does the work and where the plants come from. Ifyou grow your own plants or bor-row plants from neighbors therecan be very little or no cost at all.If you do all the work but use pur-chased prairie plants, a rain gardenwill cost approximately $3 to $5per square foot. If a landscaper

does everything, it will cost approx-imately $10 to $12 per squarefoot.

It might seem easiest to sownative wildower seed over thegarden, but experience shows thatseeding a rain garden has its prob-lems. Protecting the seeds fromwind, ooding, weeds, and gardenpests is very difficult, and the raingarden will be mostly weeds forthe rst two years. Growing plugsfrom seed indoors or dividing afriends plants is much better. Ifyou grow plugs, start them aboutfour months before moving them

to the rain garden. When the rootshave lled the pot and the plantsare healthy, they may be planted inthe rain garden


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The following pages contain conceptual planting designs and plant lists for rain gardenswith varying sun and soil conditions. Keep in mind that design possibilities for raingardens are almost limitless. Many landscape nurseries, particularly those specializing innative plants and landscaping, can provide other ideas, designs and suggested plants.

Rain Garden Designs and Plant Lists

The following eight designs and plantlists have been provided by AppliedEcological Services, Inc., Brodhead, WI.

.


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10 feetwide;full topartialshadewith claysoils

20 feetwide;full topartialshadewith claysoils


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10 feetwide;full topartialshadewith silty& sandy

soils

20 feetwide;full topartialshade

with silty& sandysoils


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10 feetwide;full topartialsunwith claysoils

20 feetwide;full topartial

sunwith claysoils


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20 feetwide;full topartialsun withsilt andsandysoils

10 feetwide;full topartialsun withsilt andsandy

soils


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The following three designs and plantlists have been provided by PrairieNursery, Inc., Westeld, WI

.


24/32


25/32

R A I N G A R D E N F O R C L A Y S O I L S A N D F U L L S U N

A R E A :

1 9 2 S q u a r e

F e e t

D e s

i g n e

d t o t h r i v e

t h r o u g

h c o n d

i t i o n s o f p e r

i o d i c w a t e r

i n l t r a t

i o n s a s w e l

l a s

d r y p e r i o d s

D e s

i g n e

d t o c o n t r o

l 4 5 %

o f a n n u a l r u n o

f f f r o m a n a v e r a g e s i z e

d r o o f

t o p

( 5 0 0 t o 7 0 0 s q u a r e

f e e t

)

I n s t a l

l a t l e a s

t 1 0 f r o m y o u r

f o u n

d a t

i o n ,

i n - l i n e w

i t h a d o w n - s p o u

t a n

d / o r

d o w n s

l o p e

t o i n t e r c e p

t t h e r o o f

t o p w a t e r

D e p

t h o f

t h e g a r

d e n

d e s

i g n e d

t o b e

3 . 5

t o 4 d e e p

t o h o l

d a b o u t

2 0 0 g a l

l o n s o f w a t e r

d u r i n g p e r

i o d s o f

h e a v y r a i n f a l

l

B L O O M

B L O O M

L A T I N N A M E

C O M M O N N A M E

A M T

T I M E

C O L O R

H E I G H T

S P A C I N G

A s c

l e p

i a s

i n c a r n a t a

R e d

M i l k w e e

d

7

e a r l y s u m m e r

r e d

3 - 5

1

B a p

t i s i a

l a c t e a

W h i t e F a l s e

I n d i g o

1


w h i t e

3 - 5

2

I r i s v e r s

i c o l o r

B l u e

F l a g

I r i s

7


b l u e

2 - 3

1

P e n s

t e m o n

d i g i t a l i s

S m o o

t h P e n s t e m o n

7


w h i t e

2 - 3

1

L i a t r i s p y c n o s t a c

h y a

P r a i r i e

B l a z i n g s t a r

8

s u m m e r

p i n k

3 - 5

1

P a r t

h e n

i u m

i n t e g r i

f o l i u m

W i l d Q u i n i n e

8

s u m m e r

w h i t e

3 - 5

1

R a t

i b i d a p

i n n a

t a

Y e l l o w

C o n e

o w e r

8

s u m m e r

y e l l o w

3 - 6

1

B o l

t o n i a a s

t e r o

i d e s

F a l s e

A s t e r

8

l a t e s u m

m e r

w h i t e / p i n k

2 - 4

1

R u d

b e c

k i a s u

b t o m e n

t o s a

S w e e

t B l a c k - E y e

d S u s a n

2

l a t e s u m

m e r

y e l l o w

4 - 6

2

V e r n o n

i a f a s c

i c u l a t a

I r o n w e e

d

8

l a t e s u m

m e r

m a g e n

t a

4 - 6

1

A s t e r n o v a e - a n g

l i a e

N e w

E n g

l a n d

A s t e r

1 2

f a l l

p i n k / p u r p

l e

3 - 6

1

S o l i d a g o r i g

i d a

S t i f f G o l

d e n r o

d

1 2

f a l l

y e l l o w

3 - 5

1

C a r e x v u

l p i n o i

d e a

F o x

S e d g e

9 6

1 - 3

1

1 8 4 p

l a n t s

R a i n

G a r

d e n s

A h o w - t

o m a n u a l

f o r

h o m e o w n e r s

2 5


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27/32

R A I N G A R D E N F O R L O A M

T O S A N D Y / L O A M

S O I L S A N D F U L L S U N

A R E A :

1 9 2 S q u a r e

F e e t

D e s

i g n e

d t o t h r i v e

t h r o u g

h c o n d


i o d i c w a t e r

i n l t r a t

i o n s a s w e l

l a s

d r y p e r i o d s

D e s

i g n e

d t o c o n t r o

l 9 0 %



d r o o f

t o p

( 5 0 0 t o 7 0 0 s q u a r e

f e e t

)

I n s t a l

l a t l e a s

t 1 0 ' f r o m y o u r

f o u n

d a t

i o n ,

i n - l i n e w


t a n

d / o r

d o w n s

l o p e

t o i n t e r c e p

t t h e r o o f

t o p w a t e r

D e p

t h o f

t h e g a r

d e n

d e s

i g n e d

t o b e

3 . 5

" t o 4 " d e e p

t o h o l

d a b o u t

4 0 0 g a l


d u r i n g p e r

i o d s o f


l

B L O O M

B L O O M

L A T I N N A M E

C O M M O N N A M E

A M T

T I M E

C O L O R

H E I G H T

S P A C I N G

A s c

l e p

i a s

i n c a r n a t a

R e d

M i l k w e e

d

7


r e d

3 ' - 5 '

1 '

B a p

t i s i a

l a c t e a

W h i t e F a l s e

I n d i g o

1


w h i t e

3 ' - 5 '

2 '

I r i s v e r s

i c o l o r

B l u e

F l a g

I r i s

7


b l u e

2 ' - 3 '

1 '

P e n s

t e m o n

d i g i t a l i s

S m o o


7


w h i t e

2 ' - 3 '

1 '

A l l i u m c e r n u u m

N o d

d i n g

P i n k

O n i o n

1 6

s u m m e r

p i n k

1 ' - 2 '

6 "


h y a

P r a i r i e


8

s u m m e r

p i n k

3 ' - 5 '

1 '

P a r t

h e n

i u m

i n t e g r i

f o l i u m


8

s u m m e r

w h i t e

3 ' - 5 '

1 '

B o l

t o n i a a s

t e r o

i d e s

F a l s e

A s t e r

8

l a t e s u m

m e r

w h i t e / p i n k

2 ' - 4 '

1 '

R u d

b e c

k i a s u

b t o m e n

t o s a

S w e e

t B l a c k - E y e

d S u s a n

2

l a t e s u m

m e r

y e l l o w

4 ' - 6 '

2 '

V e r n o n

i a f a s c

i c u l a t a

I r o n w e e

d

8

l a t e s u m

m e r

m a g e n

t a

4 ' - 6 '

1 '


l i a e

N e w

E n g

l a n d

A s t e r

1 2

f a l l

p i n k / p u r p

l e

3 ' - 6 '

1 '

S o l i d a g o o h

i o e n s i s

O h i o

G o l

d e n r o

d

1 2

f a l l

y e l l o w

3 ' - 4 '

1 '

C a r e x v u

l p i n o i

d e a

F o x

S e d g e

9 6

1 ' - 3 '

1 '

1 9 2 p

l a n t s

R a i n

G a r

d e n s

A h o w - t

o m a n u a l

f o r

h o m e o w n e r s

2 7


28/32


29/32

R A I N G A R D E N F O R S A N D Y S O I L S A N D F U L L S U N

A R E A :

1 2 8 S q u a r e

F e e t

D e s

i g n e

d t o t h r i v e

t h r o u g

h c o n d


i o d i c w a t e r

i n l t r a t

i o n s a s w e l

l a s

d r y p e r i o d s

D e s

i g n e

d t o c o n t r o

l 9 0 %



d r o o f

t o p

( 5 0 0 t o 7 0 0 s q u a r e

f e e t

)

I n s t a l

l a t l e a s

t 1 0 ' f r o m y o u r

f o u n

d a t

i o n ,

i n - l i n e w


t a n

d / o r

d o w n s

l o p e

t o i n t e r c e p

t t h e r o o f

t o p w a t e r

D e p

t h o f

t h e g a r

d e n

d e s

i g n e d

t o b e

3 . 5

" t o 4 " d e e p

t o h o l

d a b o u t

4 0 0 g a l


d u r i n g p e r

i o d s o f


l

B L O O M

B L O O M

L A T I N N A M E

C O M M O N N A M E

A M T

T I M E

C O L O R

H E I G H T

S P A C I N G

A s c

l e p

i a s

i n c a r n a t a

R e d

M i l k w e e

d

4


r e d

3 ' - 5 '

1 '

B a p

t i s i a

l a c t e a

W h i t e F a l s e

I n d i g o

1


w h i t e

3 ' - 5 '

2 '

I r i s v e r s

i c o l o r

B l u e

F l a g

I r i s

4


b l u e

2 ' - 3 '

1 '

P e n s

t e m o n

d i g i t a l i s

S m o o


4


w h i t e

2 ' - 3 '

1 '

A l l i u m c e r n u u m

N o d

d i n g

P i n k

O n i o n

1 8

s u m m e r

p i n k

1 ' - 2 '

6 "


h y a

P r a i r i e


5

s u m m e r

p i n k

3 ' - 5 '

1 '

P a r t

h e n

i u m

i n t e g r i

f o l i u m


5

s u m m e r

w h i t e

3 ' - 5 '

1 '

B o l

t o n i a a s

t e r o

i d e s

F a l s e

A s t e r

4

l a t e s u m

m e r

w h i t e / p i n k

2 ' - 4 '

1 '

R u d

b e c

k i a s u

b t o m e n

t o s a

S w e e

t B l a c k - E y e

d S u s a n

2

l a t e s u m

m e r

y e l l o w

4 ' - 6 '

2 '

V e r n o n

i a f a s c

i c u l a t a

I r o n w e e

d

4

l a t e s u m

m e r

m a g e n

t a

4 ' - 6 '

1 '


l i a e

N e w

E n g

l a n d

A s t e r

8

f a l l

p i n k / p u r p

l e

3 ' - 6 '

1 '

S o l i d a g o o h

i o e n s i s

O h i o

G o l

d e n r o

d

8

f a l l

y e l l o w

3 ' - 4 '

1 '

C a r e x v u

l p i n o i

d e a

F o x

S e d g e

( s e d g e )

6 4

1 ' - 3 '

1 '

1 2 8 p

l a n t s

R a i n

G a r

d e n s

A h o w - t

o m a n u a l

f o r

h o m e o w n e r s

2 9


30/3230

Special Rain Garden Locations

In addition to conventional lawns, there are other locations where rain gardens can be created. A rectangular-shaped rain garden (above) was located in a narrow sideyard between two homes. A new rain garden (below),now helps control runoff that would ow into a parking lot.


31/32


Rain garden designs andplant lists provided by JohnGishnock, Applied EcologicalServices, Inc. (pages 19-22)and Jennifer Baker, PrairieNursery Inc. (pages 24-29).


32/32

A how-to manual for homeowners

This publication developed by Roger Bannerman, Wisconsin Department of Natural Resourcesand Ellen Considine, U.S. Geological Survey. Special thanks to John Gishnock, Applied Ecological Services, Inc.,

Jennifer Baker, Prairie Nursery Inc. and Joyce Powers, CRM Ecosystems Inc.

Photos by Roger Bannerman, Wisconsin Department of Natural Resources.

Layout design/production by Jeffrey Strobel, and editorial assistance by Bruce Webendorfer, University ofWisconsinExtension Environmental Resources Center.

This publication is available from county UW-Extension offices, Cooperative Extension Publications, 1-877-947-7827and from DNR Service Centers.

The publication can also be viewed and printed from pdf format on the web at clean-water.uwex.edu/pubs/raingardenCopyright 2003 by the Board of Regents of the University of Wisconsin System. University of WisconsinExtension is an EEO/Affirmative Action employerand provides equal opportunities in employment and programming, including Title IX and ADA requirements.

A frosted rain gardenin autumn.

the rain garden manual for homeowners

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