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A STEP-BY-STEP GUIDE TO Landscaping FOR Clean Water AND Healthy Streams

THE OREGON Ra n G rden Guid

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The Oregon Rain Garden Guide: Landscaping or Clean Water and Healthy Streams2

The Oregon Rain Garden Guide:Landscaping for Clean Water and Healthy Streams

Text by Robert Emanuel and Derek Godwin, Oregon Sea Grant Extension, Oregon State University (OSU);and Candace Stoughton, East Multnomah Soil and Water Conservation District.

Sample rain garden layouts by Heidi Brill. Plant list compiled and edited by Teresa Huntsinger, Oregon EnvironmentalCouncil. Other signi cant contributors include Angela Boudro, Jackson Soil and Water Conservation District; LindaMcMahan, OSU Extension Service, Yamhill County; Joy Jones, OSU Extension Service, Tillamook County; and NeilBell, OSU Extension Service, Marion County. Editing by Rick Cooper, graphic design by Patricia Andersson, Oregon SeaGrant, OSU.

Cover artwork: Rain Garden painted by John C. Pitcher Good Nature Publishing 2009.www.goodnaturepublishing.com 800-631-3086

This project has been unded in part by the United States Environmental Protection Agency under assistance agree-ment CP-0045105 to the Oregon Department o Environmental Quality. The contents o this document do notnecessarily refect the views and policies o the Environmental Protection Agency, nor does mention o trade namesor commercial products constitute endorsement or recommendation or use.

Many thanks to those who reviewed this document, plant lists, and sample planting designs or accuracy and appro-priateness. Special thanks to those who made contributions o photos or text.

2010 by Oregon State University. This publication may be photocopied or reprinted in its entirety or noncom-mercial purposes. To order additional copies o this publication, call 541-737-4849. This publication is available in anaccessible ormat on our Web site at http://seagrant.oregonstate.edu/sgpubs/onlinepubs.html

For a complete list o Oregon Sea Grant publications, visit http://seagrant.oregonstate.edu/sgpubs

This report was prepared by Oregon Sea Grant under award number NA06OAR4170010 (project number E/BET-02-PD) rom the National Oceanic and Atmospheric Administrations National Sea Grant College Program, U.S. Depart-ment o Commerce, and by appropriations made by the Oregon State legislature. The statements, ndings, conclu-sions, and recommendations are those o the authors and do not necessarily refect the views o these unders.

Oregon Sea Grant, Corvallis, Oregon ORESU-H-10-001

The production o this guide was part o Stormwater Solutions,a collective public education e ort involving several partners.Partners responsible or the production o this guide includethe ollowing:

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The Oregon Rain Garden Guide: Landscaping or Clean Water and Healthy Streams

Contents

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4The purpose o this guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4What is a rain garden? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Why build a rain garden? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5Building a Rain Garden: A Step-by-Step Approach . . . . . . . . . . . . . . . . . . . . 6 STEP1 : Observe and map your site . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Determine how much area the rain garden will treat. . . . . . . . . . . . . . . . . 6

STEP2 : Determine the location of the rain garden . . . . . . . . . . . . . . . . . . . 6Go with the fow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Respect the fow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7Divert the fow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7Regulations, permits, and design modi cations . . . . . . . . . . . . . . . . . . . . 8Measure the slope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

STEP3: Assess soil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Testing in ltration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Determining soil texture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Interpreting the in ltration test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11

STEP4 : Determine the size of the rain garden . . . . . . . . . . . . . . . . . . . . . . . 11Rain garden depth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12Dig sa ely! . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13Delineate the rain garden . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13Getting water to the rain garden . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13Disconnec t ing downspou t s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15Designing or overfow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16Keys to success . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17

STEP5 : Constructing a rain garden . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17Excavating, grading, and berms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17Grading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18Plumbing the rain garden . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18To amend or not to amend? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19

STEP6 : Choose the right plant for the right place . . . . . . . . . . . . . . . . . 20Planting zones and plant selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20Compost . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20Key plant characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22Planting tips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22A note about invasive species . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22Mulching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23Watering a rain garden . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

STEP7 : Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24Weeding, pruning, and mulching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24Dont drown your plants! . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

A note about Oregons regions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Sample Rain Garden Layouts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28Rain Garden Plant List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

For more information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

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Introduction

Figure 1:Cross-section of atypical rain garden.(Graphic by East Multnomah Soil and Water Conservation District[EMSWCD])

The purpose o this guideThe Oregon Rain Garden Guidewas written to helpOregonians learn how to design and build rain gar-dens to treat the stormwater runo rom their ownhomes or businesses. Rain gardens are gardenswith a purpose; they help reduce the amount o ex-cess water and associated pollutants reaching locallakes, streams, and bays. Ultimately this results inhealthier waterways, sh, other wildli e, and people.

This how-to guide provides in ormation speci cto Oregons conditions, including the rain all andappropriate plants or your site. You dont have tobe a stormwater, garden, or landscape pro essionalto use this guide. It provides the necessary in or-mation to sa ely build and maintain a rain garden,along with re erences or more detailed guidance

or special conditions. You may also contact theauthors and partners directly or more in ormation.

What is a rain garden?A rain garden is a sunken, generally fat-bottomedgarden bed that collects and treats stormwaterruno rom roo tops, driveways, sidewalks, parkinlots, and streets. Rain gardens help mimic natural

orest, meadow, or prairie conditions by in ltrat-ing stormwater rom hard sur aces. A variety o planting plans are included in this manual or yourre erence.

Rain gardens keep our watersheds healthy by

reducing fooding by absorbing rain water romhard sur aces

ltering oil, grease, and toxic materials be orethey can pollute streams, lakes, and bays

recharging groundwater aqui ers by allowingwater to soak into the ground

providing bene cial wildli e habitat

RAIN GARDEN DICTIONARY:Impervious surfaces are areas that do not allow rain or snowmelt to in ltrate or soak into the soilbelow the sur ace ( or example, roo s, driveways, roads, sidewalks, and patios). Some ground areasthat have been severely compacted rom heavy equipment or oot tra c may also be consideredimpervious i most o the water runs o the sur ace when it rains.

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Why build a rain garden?When the Paci c Northwest was covered with

orests and prairies, rain all slowly dripped throughbranches and vegetation, seeped through du ,and sank into the ground as it slowly percolated tonearby water bodies. As parts o our landscapesbecame more developed, the rain all that lands onhard sur aces was routed into pipes, ditches, andstorm drains. Much o that runo is routed directlyto streams or into the sewer system. The result?Too much water fowing in a short amount o time, carrying pollutants that negatively a ect thehealth o our streams, lakes, and estuaries. Today,managing stormwater runo by in ltrating it intothe ground is one o the simplest ways to activelyprotect our streams. Rain gardens help us restorethe natural water cycle in the landscape, which iscritical to ensure healthy streams in both smalltowns and large cities.

Do rain gardens attract or breedmosquitoes?No. For reproduction, mosquito larvae requirea number o days in standing water. Mosturban mosquitoes breed in places like junkpiles where there are old tires or tin cans. In awell-designed rain garden, water is rarely stand-ing long enough or mosquito reproduction.Ideally, a rain garden should drain so that waterwont be standing in it or more than 48 hours.For more in ormation, see Mosquitoes atentomology.oregonstate.edu/urbanent/.

Figure 2 (top): A newly installed rain garden in

Tillamook County, Oregon.Figure 3 (middle): An established rain garden inPortland, Oregon (by Blossom Earthworks).

Figure 4 (bottom): Streams in the Paci c Northwestare normally buffered from pollution and sudden

ashes of water by their surrounding forests and grasslands. In an urban environment, water fromroofs and streets is often piped directly into streams,delivering pulses of polluted, damaging water and sometimes causing localized ooding.

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HORIZONTAL DISTANCE (233)

LINE LEVEL

STAKE

RISE (18) STAKE

Regulations, permits, and designmodi cationsSome cities and counties have speci c regulationsregarding disconnecting downspouts, routing orpiping water o -site, and setbacks to structures,steep slopes, and property lines. They may alsorequire a permit. Always check with your citysbuilding or planning department i you live withincity limits; otherwise, check with your countygovernment.

Rain gardens may be designed with impermeableliners, rock trenches, and piping to sa ely routewater away rom structures and o -site. These de-

signs would allow you to build rain gardens closerto structures, on steep slopes, in soils that dontdrain well, and in other challenging situations.However, these designs are beyond the scopeo this guide. We recommend that you contact alicensed landscape pro essional or engineer orassistance with these alternative designs.

Measure the slopeTools needed: Two stakes Survey line or string Line level Measuring tape Calculator

Steps:Measure and calculate the slope o the site to as-sess how water will be routed to and rom your raingarden. It is critical to make sure your property hasa slope o less than 10 percent be ore constructing

a rain garden there.1. Place stakes in the ground at the top and bottom

o the slope to be calculated.

2. Attach a survey line (or any heavy-duty string) tothe two stakes. Be sure that the line touches theground on the uphill stake. Use the level to makesure the line is level.

3. Measure the horizontal distance (along the line)between the two stakes.

4. Measure the rise (vertical distance) rom theground up to the line on the downhill stake.

5. Calculate the slope by plugging your numbersinto the ollowing ormula:

Note: both measurements must use the sameincrements ( or example, inches).

slope =RISE

HORIZONTAL DISTANCEx 100%

18"

Example:RISE = 18"HORIZONTAL DISTANCE = 233"

x 100%233"

7.7 % =

G r a p h

i c : E

M S W C D

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STEP3 : Assess soilThe ability o soil to drain water is one o the mostimportant considerations or understanding thesite and properly sizing a rain garden. An in ltrationand texture test will help you determine the soilscapacity to absorb and percolate water down intothe lower layers.

Testing in ltration

1. Dig a test hole in the area where the rain gardenwill be built. Try to site the hole in the middle o the planned rain garden. Dig a hole to the expect-ed depth o the rain garden ( rom grade to the topo the rain gardens base). Note that ideally, thistest should be done when soils are not rozen andwhen groundwater levels may be highest, such asin the spring.

2. Fill the hole with water to just below the rim. Thisshould be the same depth o water expected i therain garden lled to the rim. Record the exact timeyou stop lling the hole and the time it takes todrain completely.

3. Re ll the hole again and repeat step 2 two moretimes. The third test will give you the best mea-sure o how quickly your soil absorbs water when

it is ully saturated, as it would be during a rainyperiod o the year or during a series o stormsthat deliver a lot o rain all in a short period o time. Building a rain garden to handle theseconditions is a way to be sure you will not causedamage to your own or a neighbors property.

4. Divide the distance that the water dropped by theamount o time it took or it to drop. For example,i the water dropped 6 inches in 12 hours, then 6divided by 12 equals 1/2 inch per hour o in ltra-tion. I the slowest in ltration rate measured o the three trials is less than 1/2 inch per hour, thenyou should dig another 3 to 6 inches deeper andrepeat the above steps. Repeat this process atvarious depths down to 2 eet, or until you have atleast 1/2 inch per hour in ltration.

! Note : Soils with drainage o less than 1/2 inch perhour are not appropriate or rain gardens with-out signi cant modi cations in design. Consulta licensed landscape pro essional or engineer orassistance in these circumstances.

1

2

3

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Determining soil texture

1. Take a hand ul o the soil you have excavated

rom your in ltration test. Pulverize it in yourhand and remove any bits o organic matter orobvious rocks.

2. Wet it with a small amount o water and rub itbetween your thumb and index nger. Dontsaturate it until it is runny mud. You might eelstickiness, grittiness, or smoothness. The grittierthe eel, the more sand is present in your soil.The slicker the soil, the more clay in it. Smoothsoils are sometimes an indicator o a ne silt orloam. Discard the soil.

3. Next, take another sample in your hand. Wet ituntil it has the consistency o dough. You shouldbe able to orm a ball that holds together withthe soil in your palm. I you cannot get the ball to

orm, then your soil is very sandy. In most soils,however, you should be able to create a roughball.

4. Knead the soil together between your thumb andngers and attempt to orm a ribbon. As you

build the ribbon, it will either hold together orbreak o . I the soil breaks quickly in the processthen it likely has a high sand content. I the rib-

bon orms quickly and stays strong, it has moreclay.

I the soil orms a ribbon less than 1 inch inlength be ore it breaks, the soil is sandy or silty.

I the soil makes a ribbon 1 to 2 inches in lengthbe ore it breaks, the soil is clayey.

I the soil makes a ribbon greater than 2 inchesbe ore it breaks, it may not be suitable or a raingarden constructed without pro essional help,depending on how ast the soil drains during the

in ltration test.

Figure 7a: Conducting a soil feel test by making a ball with the moistened soil, tosee how easily it falls apart as well as what texture it has (sticky, silky, or gritty).(Photo: Gina Emanuel)

Figure 7b: Using a soil ribbon to test soil for clay, loam, or sand content. Thelonger and rmer the ribbon, the more clay content in the soil.(Photo: Gina Emanuel)

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The Oregon Rain Garden Guide: Landscaping or Clean Water and Healthy Streams 1

Interpreting the in ltration test

Building a better soilAmending with compost is recommended toimprove initial plant and microbial health. I your soil has high clay content, soil amend-ments may be needed to improve conditions

or good plant health. Sites with very high claycontent and low drainage are usually inappro-priate or the types o rain gardens describedin this guide, without signi cantly altering thedesign or better drainage (such as addingsubsur ace drain pipes and drain rock).

I you plan to amend the soil, a typical soilmixture contains 20 to 40 percent organicmaterial (compost); 30 to 50 percent clean,coarse sand; and 20 to 30 percent top soil.

Note: do not add sand to a highly clayey soil.Soils are commonly amended to a depth o 1824 inches.

STEP4 : Determine the sizeof the rain gardenAlways check with your local planning department,public works, or stormwater utility be ore design-ing your rain garden. I your local jurisdiction doesnot have a recommended size calculation or arain garden, then we recommend the size o therain garden be at least 10 percent o the impervi-ous sur ace draining to the garden. Rain gardensshould ideally be between 6 and 24 inches deep.

To use this number, your soil should drain at least1/2 inch per hour or greater. Compare the result o

your soil in ltration test with the table above, ora good idea o how your soil infuences the size o the rain garden. Rain gardens o 10 percent and 1/2inch minimum in ltration rate should treat a largemajority o storms in Oregon.

Using the area o impervious sur ace that youcalculated in Step 1, multiply this by 0.10 (or 10percent). The result will be the area o the raingarden in square eet. The calculation is:

Drainage rate Recommendation

Less than 1/2 inch per hour Do not build a rain garden on this site without pro essionalassistance.

Between 1/2 and 1 inch/hourLow in ltration or a rain garden. Homeowners may want to builda larger or deeper garden, or likewise plan or additional overfowduring high-rain all storms.

Between 1 and 1 1/2 inches/hour Adequate in ltration or a rain garden. Plan or su cient overfowduring high-rain all storms.

Between 1 1/2 and 2 inches/hour Adequate in ltration or a rain garden. Plan or su cient overfowduring high-rain all storms.

Faster than 2 inches/hourHigh in ltration or a rain garden. Design should eature ewermoisture-loving and more drought-tolerant plants. The rain gardenmay also be sized to hold smaller amounts o water, have a deepermulch layer, or have denser plantings.

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(Length of surface area x Width of surface area)x .10 = total rain garden area

An example: 30 eet x 12 eet = 360 square eetx .10 = 36 square eet o rain garden

The more impervious area you want to treat, thebigger your garden. The size o your rain gardenwill also depend on the space available and yourbudget. I you dont have enough space, you canbuild multiple rain gardens or build a smaller oneand plan or it to overfow more o ten.

Note: Rain gardens should be a minimum o veeet wide to accommodate gentle side slopes that

will host plants and minimize soil erosion.

Rain garden depthMost rain gardens should be between 6 and 24inches in ponding depth with 24 inches o ad-ditional depth or sa ety. This means that raingardens range rom 8 to 28 inches in depth. Thetable below is a general guide or rain garden pond-ing depths based on di erent drainage rates. Adddepth where overall size is restricted by setbacks,

structures, vegetation, or other obstacles.

Drainage rate Suggested rain garden ponding depth

Between 1/2 and 1 inch/hour 1224 inches

Between 1 and 2 inches/hour 68 inches

Faster than 2 inches/hour 6 inches

Typical ponding depth624 inches

Figure 8: Pondingsurface is denoted by the do ed line.

(Graphic: EMSWCD)

Note: remember to account or the addition o mulch when you plan or your nished depth (see

Mulching on page 23). For example, i you areadding 3 inches o mulch to your nal planted gar-den and it needs to be at least 12 inches deep, youmust excavate to a depth o 15 inches rom grade.

RAIN GARDEN DICTIONARY:The size o a rain garden re ers to the volumeo water it can hold be ore the water overfowsat the exit point. This volume is described interms o ponding depth and square eet o

sur ace area (depth x width x length).Ponding depth is the depth at which the watercan pond be ore it fows out o the rain garden(see Figure 8). It is measured rom the sur aceo the rain garden at its lowest point to theelevation o the outlet. Rain gardens gener-ally should range between 6 and 24 inchesin ponding depth, adding 24 inches o extradepth below the outfow or sa ety.

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Dig sa ely!Its the law in the state o Oregon to call the UtilityNoti cation Center by dialing 811 or 1-800-332-2344be ore beginning any excavation. The service is

ree and convenient or homeowners, contractors,excavators, landscapers, etc. Anyone planning todig must contact the Center at least two businessdays prior to digging,in order or the undergroundutilities to be located and accurately marked usingcolor-coded paint. For more in ormation ondigging sa ely, visit the OUNC Web site:www.digsa elyoregon.com.

Delineate the rain garden

Use a garden hose, string, stakes, or marking paintto delineate the boundary o the rain garden on thesite. Be ore you dig, be sure to note any existingutilities or vegetation that might be damaged bydigging (see note above).

Getting water to the rain gardenYour garden will not actually be managing storm-water i it does not collect rain water rom yourhomes impervious sur aces. That means youmust nd ways to get water rom your collection

points to your garden, sometimes by diggingtrenches, running gutter extenders, or even build-ing arti cial streams that run only when the rain

alls. The water may be routed using a pipe, rocktiles, or other hard sur aces, or a small swale (ditch)lined with rock (3/4-inch diameter, washed drainrock or pea-sized gravel). I using a pipe, we recom-mend a 4-inch diameter ABS.

I not using a rock-lined trench, the outlet o therouted water and inlet o the rain garden should belined with rock (again, 3/4-inch diameter, washed

drain rock or pea-sized gravel) to prevent erosion.In addition, a 4-inch-wide strip o grass could beused to lter and settle sediment rom your rainwater be ore it enters the rain garden.

Figures 9a and b: Delineating rain garden boundaries with a garden hose (top)and marking paint (above). (Photos by Robert Emanuel, OSU)

Figure 10:Moving water from a gutter to a gardencan be as simple as a piece of buried 4-inch drain pipe.Note that the pipe is buried at least 12 below thesurface as required by Oregons plumbing code. Seenote on page 19. P h

o t o :

P o r t

l a n d

B u r e a u o

E n v i r o n m e n t a l

S e r v

i c e s

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Figure 13 (right):A dry stream bed conveys water across a surface before itenters a rain garden. (Photo: Judy Scott, OSU)

Figure 11:Using a rock-lined trench to convey water across a walkway(Photo: Portland Bureau of Environmental Services [BES])

Figure 12:Trench drain through a sidewalk at a building in Portland.(Photo: Derek Godwin, OSU)

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Disconnecting downspoutsDisconnecting downspouts is an important parto rain garden construction. Avoid creating sa etyand structural problems when disconnecting anydownspouts rom your storm sewer by ollowingthese sa ety guidelines: Dont disconnect a downspout in an area that

is too small to drain the water properly. Disconnected downspouts must be extended

to discharge water at least 6 eet rom a struc-ture with a basement or 2 eet rom a crawlspace or slab oundation.

Direct water away rom your structure, a retain-ing wall (by at least 10 eet), a septic drain eld,or an underground storage tank.

The end o the downspout extension must beat least 5 eet away rom a neighboring propertyand 3 eet rom a public sidewalk. Do not directwater toward a neighboring property, especiallyon a steep slope.

Steps for disconnecting:

1. Measure the existing downspout rom the topo the standpipe, and mark it at least 9 inchesabove the standpipe. A standpipe is the pipeleading into the below-ground storm sewer.

2. Cut the existing downspout with a hacksaw atthe mark. Remove the cut piece.

3. Plug or cap the standpipe. Do not use concreteor another permanent sealant.

4. Attach an elbow to the newly cut downspout byinserting the elbow over the downspout. Thenuse at least two sheet-metal screws to securethe two pieces.

5. Measure and cut the downspout extension sothat when it is attached, you will be ollowingthe sa ety guideline above. Fit the extensionover the elbow and attach it with sheet-metalscrews.

6. I the extension does not connect directly to abelow-ground pipe or lead into a rain garden,use a splash block or gravel to prevent soilerosion.

7. Remember that each section should unnel intothe one below it. All parts should be securely

astened together with sheet-metal screws.

Be sure to maintain your gutter system. Inspectit regularly or leaks, sagging, holes, or otherproblems. It is a good idea to annually inspectand clear debris rom gutters, elbows, and otherconnections be ore the rains arrive.

This material is condensed from How to ManageStormwater: Downspout Disconnection, City of Portland Bureau of Environmental Servicespublication BS 07011. It is used here with permissionof the City of Portland, BES. The full document canbe found at www.portlandonline.com/bes/index.cfm?c=46962&a=188637.

Figure 14.Downspout connected to downspoutextension that directs ow away from a buildings

foundation. Note sheet-metal screws.(Photo: Robert Emanuel, OSU)

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Designing or overfowWhen properly sized, a rain garden is designedto handle roughly 8090 percent o the waterthat alls on a given impervious sur ace. There-

ore, extreme events should be considered whendesigning your garden. For this reason, it is criticalto include plans or overfow. This should be anotch or a pipe in the berm, at least 2 inches lowerthan the berm. The overfow could lead to one o several options:

a fat area in your home landscape where watercan be sa ely absorbed,

another rain garden, a French drain or rock- lled soakage trench, a swale or drainage ditch, or return stormwater to its original destination be-

ore the rain garden was built (such as a publicsewer, street gutter, storm drain, or pipes andcatch basin).

Be sure to discuss your plans or overfow withyour local planning department. They typicallyhave speci c, approved locations or draining theoverfow o -site. They may also require a permit

or a rain garden.

Figure 15:Curb-cut inlet for a parking lot and an over ow device (pipe and screen) for a parking lot in Gresham, Oregon.(Photo: Derek Godwin, OSU)

Figure 16: PVC pipe out ow from a coastal Oregon rain garden. The rocks,mulch, and gravel help protect the area from erosion.(Photo: Robert Emanuel, OSU)

Figure 17:A rain garden in Gresham, Oregon, llswith rain. Note the use of rocks at the out ow pointnear top. (Photo: City of Gresham)

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Note: For smaller gardens, or gardens in high rain-all areas with soils with low in ltration rates, you

will need to take extra care in routing the overfow

away rom the garden in a sa e manner.

Keys to successPermits and design modi cations:Check with your local government (city or countyplanning department) to nd out whether you can legally build a rain

garden (and whether you need a permit) get in ormation on disconnecting downspouts

or routing water o the site learn about any design requirements or setbacks

You may decide that you need the help o a licensedlandscape pro essional or engineer.

Be kind to trees:Its a good idea to avoid placing a rain gardenbeneath the drip line o large trees. The tree rootswill be damaged by the excavation and may also beoverwhelmed by the amount o water that poolsbeneath them.

When is the best time to build?The ollowing schedule is recommended to pre-vent soil compaction, maintain the soils ability toin ltrate stormwater, and minimize the need orwatering the plants: Conduct site assessments and design the gar-

den in the all, winter, and spring when the soil iswet but not rozen;

Excavate and build the garden when the soil isdry enough to work with easily; and

Plant vegetation in the all and as early as pos-sible the ollowing spring.

STEP5 : Constructing a rain gardenExcavation, grading, and berms

Plan to place the spoils to the outside edge o thegarden and away rom the infow point. Use thespoils and any excess soil amendments to ormthe berm that bounds the rain garden on oneor more sides, depending on the terrain. Bermsshould be built to have at least 2 inches o heightabove the elevation o the outlet.

Whether digging by hand or machine, excavatethe soil rom the outer edge o the rain garden tominimize soil compaction.

We recommend that the slope on the rain gardenberm be at least 18 inches o horizontal length to6 inches o vertical height (3:1) or fatter on bothsides o the berm. I the rain garden is 12 inches indepth, you will need to have 36 inches o slope oneither side o the berm.

Figure 18:Excavator is located outside of the rain garden in order to make sure the machine does not compact soil in the rain garden.(Photo: Robert Emanuel, OSU)

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Figure 20: Using a combination of a line level and ameasuring tape allows you to grade the base of thegarden so that water will not pool in a particular location but will spread across the entire surface asevenly as possible.(Photo: Robert Emanuel, OSU)

Figure 21:Four-inch ABS storm-drain pipe connectsmoothly to a downspout from a roof to a rain gardein Paci c City, Oregon.(Photo: Robert Emanuel, OSU)

Plumbing the rain gardenThe overfow pointeither a swale or a pipeshould be at least 2 inches below the top o theberm on the downhill side. Similar to the inlet,you place some rock, tile, or other hard materialsaround this point and at the pipe out all to mini-mize erosion. Plants can also be used to reducesoil erosion.

Where pipes are used or infow and outfow, grad-ing is important to keep erosion at the exit pointto a minimum and to keep water rom backing uptoward your home or other built structure. A goodrule o thumb is to grade your pipes to drop about1 inch or every 10 eet.

GradingThe rain garden sizing process assumes the bottomo the garden is level and the sides are graded to a3:1 slope. Even i the rain garden is constructed ona slight slope, the bottom o the garden should beapproximately level to allow water to be distributedevenly throughout. We recommend you use a linelevel, stakes, and measuring tape to ensure thatthe total sur ace area and depth (storage volume)are built as designed in Step 3. Do this by placinga string across the sur ace and hanging a line-levelon it. Then measure the distance rom the string tothe soil sur ace at requent intervals. You should dothis throughout the gardens ponding sur ace (seeFigure 19, below).

Figure 19: Grading is made simpler by using four stakes, one at the in ow point and three at the

opposite or lower end of the rain gardenincluding,most importantly, the out ow point.(Photo: Robert Emanuel, OSU)

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Note: Oregon State Plumbing Code requires thatany buried utility pipe should be at least 12 belowthe soil level starting at the downspout. It also

requires underground plumbing to be a durablematerial such as Schedule 40 ABS or PVC. Whilecorrugated plastic pipes are requently ound inrain gardens (including some photographed in thisguide), these materials may not last, especially incolder climates. I using an infow pipe buried 12inches deep, a rain gardens nished depth willneed to be between 14 and 18 inches.

To amend or not to amend?Rain gardens depend on healthy plants and soilsto capture, clean, and lter the stormwater runo .As mentioned in Step 1, your soils may need tobe amended to ensure strong plant survival andmicrobial health. Where possible, your existing soilshould be tilled to 18 to 24 inches deep i amend-ing with compost, topsoil, or sand. See note onpage 20.

Figure 24:An out ow notch in a Portland, Oregon, rain garden, protected byrock to prevent soil erosion.(Photo: Robert Emanuel, OSU)

Figure 22:Four-inch ABS pipes here will convey water from this building into a rain garden. Pipes like thesemust be graded to drop about 1 inch for every 10 feetso water ows away from the building but does notbuild up too much velocity by the time is arrives in therain garden. (Photo: Robert Emanuel, OSU)

Figure 23:The point where water enters a rain garden should be well armored with rock and plants (beach strawberries here) to prevent erosion.(Photo: Robert Emanuel, OSU)

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STEP 6: Choose the right plantfor the right place

Fertilizers and pesticides o ten contribute to storm-water pollution in streams and lakes. Since raingardens are designed to treat stormwater runo , itis very important to choose plants that can surviveand thrive without chemical inputs. It is also goodpractice to choose plants and design your garden torequire minimal to no extra water.

Planting zones and plant selectionPlants vary in their tolerance o certain conditions,such as shade, fooding, moisture, and cold tem-

peratures, while maintaining their ability to surviveand grow. Rain gardens have zones that vary inwet and dry conditions and possibly sunlight andshade; there ore, plants need to be selected basedon their tolerance to these conditions and placedin the corresponding zone to survive and thrive.Furthermore, plants need to be chosen based ontheir ability to survive in the climate relative to theregion in Oregon in which they are planted (that is,Willamette Valley, coast, southwest, central, andeast). Rain gardens are generally meant to be lowmaintenance.

CompostCompost helps the soil hold moisture, increasemicrobial activity, improve its ability to lter andadsorb pollutants, and increase plant survival in the

rst ew years as it slowly biodegrades. Be sure touse weed- ree mixes.

! Note: Rain garden plants do not have to be wet-land or water plants. In act, they should be able totolerate drying out or long periods with little to nosupplemental irrigation, depending on where youlive in Oregon and how long the plants have beenestablished.

Rain gardens can be divided into three zones, rela-tive to their wet and dry conditions: moist, moderate,and dry. I you select plants rom the lists provided inthis guide, be sure to pay attention to their designa-tion as tolerant o moist, moderate, and drysoil conditions. Use plants that are designated asdoing best in moderate and dry conditions onlyon the slopes or otherwise dry parts o the garden.Do not put a plant that cannot tolerate wet eet inthe bottom or wettest part o your garden, because itcould drown during rainy periods.

Soil type will also infuence the plants and the sizeo di erent moisture zones. For example, rain gar-dens built in high-clay or slow-draining soils shouldbe planted with more plants that tolerate wet

eet, while rain gardens in sandy or ast-drainingsoil can be planted with more dry-adapted plants(listed here with moderate or dry designations).In ast-draining rain gardens, group your moisture-loving plants within a ew eet o the infow points.

Figure 25:Rock, gravel, and sedges protect the in ow point in a rain garden.(Photo: Chris LaBelle, OSU)

RAIN GARDEN DICTIONARY: Zones of wet and dry conditions Moist: plant pre ersmoist soil and tolerates

dry soil other times o the year. Moderate: plant can tolerate moist and dry

soils equally. Dry: plant tolerates and even thrives in dry

soil during most o the year.

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Filling up the rain garden and watching it drainseveral times will help you visualize where waterpools and where it drains quickly. This will helpyou choose the right plant or the right place.

Visit local examples o rain gardens to get ideaso what plants thrive and how the design worksin your local area.

Because this guide was written with most o Or-egon in mind, we recommend that gardeners usethe lists and designs provided here as suggestions,not as ironclad rules to ollow. Be creative, and beprepared to experiment with the garden; gardenareas and conditions are always variable, and no

design is ail-sa e.

Remember that plants can do some o the workto make a rain garden easier to maintain. Someespecially tough plants, such as sedges or bunchgrasses, should be grouped around eatures likeinfow and outfow points, to slow down wateras it enters the rain garden. Use groundcoverson berms and other areas where erosion is aconcern. Several designs are suggested on pages2835.

! The area around your infow will retain the mostmoisture in your rain garden, meaning that whatyou plant there must be the most tolerant o moistsoil.

Figure 26: Planting zones re ect the areas where the garden will have the most and least water when ooded, aswell as during the dry season. The graphic on the left illustrates the topographic zones of the rain garden, thegraphic on the right illustrates zones of high and low soil moisture during the dry season. (Graphic: Robert Emanuel, OSU)

Figure 27:Planting zonesin this cross section illustrawhere soil will be moistduring the wet season.(Graphic: EMSWCD)

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Key plant characteristicsOther plant characteristics and plant selectionWhile rain gardeners should ocus on selectingand placing plants that may tolerate more or lesswater, there are other characteristics to note.Remember, rain gardens can and should be attrac-tive eatures in your landscape, rather than justplaces to treat stormwater. Other characteristics toconsider include: What is the plants height and width? Does the plant have attractive oliage, fowers, or

ruit? Does it attract bene cial insects and wildli e?

Does it look good with neighboring plants andlandscape? Seasonality Shade tolerance Temperature requirements

! Remember that plants grow! This simple actshould keep you rom overplanting your rain gar-den or placing plants too close together. Respecttheir ultimate size requirements and keep in mindthat these vary throughout Oregon.

Planting tipsWhen planting, be sure to dig a planting hole atleast as big as the pot, i the soil has been amend-ed. I you are planting into unamended soil, diga hole that is at least twice the diameter but thesame depth as the pot. Most native and nonna-tive plants need to be planted at the same depthas they were growing in their pots. Leave somecompost and soil mixture mounded at the bottom,as appropriate, to keep your plant at the same levelas it was in its original container.

Care ully remove the plant rom its container. I theplant roots have ormed a solid mass around theoutside o the pot, gently loosen them or care ullyscore the outside layer with a sharp kni e. Lower theroot ball into the planting hole slowly, to preventcracking or breaking o the soil around the roots.I the root ball was opened up, spread some o theroots over the mound in the center o your hole.

Back ll your hole with well-drained soil rich incompost, being care ul to make sure you do notcover the crown o the plant i it was exposed in

the original container. Be sure to rm the soilaround the plant and water well with a slow streamo water or soaker attachment.

A note aboutinvasive speciesInvasive plants such asEnglish Ivy, Japaneseknotweed, spurge laurel,

or butterfy bush cost Oregonians millions

o dollars in control, prevention, and directeconomic losses. An invasive plant is one thatescapes cultivation and multiplies in otherhabitats, to the near exclusion o species thatwould occur naturally.

Gardens and gardeners are among the mostimportant pathways or invasive plants tomove into new places. You can help stopthe biological invasion by eliminating knowninvasive plants rom your garden; preventingthe introduction o new, aggressive plants;

and replacing nonnative invaders with riendlynative plants in your landscape.

For common invasive plants to avoid as wellas some excellent alternatives, consult thepublication GardenSmart Oregon, available atwww.oregoninvasivespecieshotline.org andthrough your local Soil and Water Conserva-tion District or OSU Extension Service o ce.

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MulchingMulch is another important part o the raingarden. It will help shade the soil and keep it cooland may increase soil moisture during the drysummer and all months. The right mulch can alsohelp control weeds. More importantly, microbialactivity in the mulch helps to break down someo the common pollutants in stormwater. For thisreason, we recommend always applying mulch tonew rain gardens and maintaining some mulch inestablished ones.

Double-shredded coni er bark mulch (also known asbark dust) is probably the most commonly usedin landscape plantings in the Paci c Northwest.Douglas- r and hemlock are the most commonlysold barks, although pine bark is also available. Barkmulch is available in a range o grades, rom nethrough medium to large bark nuggets. We recom-mend using ne-grade bark mulch rather than nug-gets, as the latter will foat. We do not recommendusing sawdust or grass clippings, as these materialswill alter your soil chemistry and can a ect the abil-ity o the garden to support healthy plants.

Apply mulch at a rate o 23 inches evenly across

the rain garden on the edges or slopes o your raingarden. I you choose not to use bark mulch in thelowest point o the garden, then be sure to apply a2- to 3-inch depth o compost instead.

Rocks and gravel are o ten used at infow and outfowareas to dissipate energy rom water and preventerosion. They will also make maintenance in the raingarden easier. Rock and gravel are important designelements that can add interest to the rain garden.Washed pea gravel is an attractive small-grade rock

or use in the base o the rain garden.

Compost is another alternative or covering thebase o the rain garden. It will not suppress weedsas well as wood chips or other materials, but it willsucceed in adding ertility to the soil and in lter-ing pollutants. More nely textured compost isless likely to foat in heavy rains. Apply compost atthe same rate as indicated in the chart to the right.

How much mulch?To calculate the total cubic yards o mulch needed

or your rain garden project, ollow these steps:

1. Multiply the length o your rain garden by thewidth to nd the square ootage.

2. Multiply that square ootage by 0.25, which willequate to 3 inches o mulch.

3. Divide that value by 27 to yield cubic yards o mulch needed or your project.

The steps above can be used to quickly esti matethe necessary amount o mulch to purchase basedon various depths o mulch. Remember not topile mulch alongside the stem o plants. Mulchis moist and can lead to rotting around the stem.Also, remember to break up any mulch that maybe dry or clumped together as you spread it overyour rain garden.

For more information on mulches, please consult:Bell, N., D. M. Sullivan, and T. Cook. 2009.Mulch-ing Woody Ornamentals with Organic Materials. EC 1629-E. extension.oregonstate.edu/catalog/pdf/ ec/ec1629-e.pdf

Cubicyards of mulch

Rain garden square feet andmulch coverage based on depth

1 2 3

1 338 sq. t. 158 sq. t. 108 sq. t

2 676 sq. t. 316 sq. t. 216 sq. t.

3 1,014 sq. t. 474 sq. t. 342 sq. t.

4 1,352 sq. t. 632 sq. t. 432 sq. t.

5 1,690 sq. t. 790 sq. t. 540 sq. t.6 2,028 sq. t. 948 sq. t. 648 sq. t.

7 2,366 sq. t. 1,106 sq. t. 756 sq. t.

8 2,704 sq. t. 1,264 sq. t. 864 sq. t.

9 3,042 sq. t. 1,422 sq. t. 972 sq. t.

10 3,380 sq. t. 1,580 sq. t. 1,080 sq. t

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Watering a rain gardenEven a ter you have chosen and care ully plantedthe right plant in the right place and mulchedthe garden, it is important to make sure new plantsget su cient water during their rst and possiblysecond dry summer season, until they are ullyestablished. This is especially true i the rain gardenwas planted in the spring or summer.

As with any watering regime, water deeply andslowly during the coolest time o the day (eveningsi possible). Soaker attachments or soaker hosesare particularly use ul or this purpose. Use a soilprobe or stick to check whether moisture is pres-ent in the rain garden at a depth greater than 23inches.

A ter the rst or second dry season, dependingupon how good the plants look and how hardy theyare, you may be able to stop watering altogetherand depend on rain entirely. Remember that themore native plants you use in your rain garden andlandscape, the less supplemental water youll needto apply during drought periods.

STEP7 : MaintenanceWeeding, pruning, and mulchingYou will need to weed your rain garden during the

rst couple o years. Try to get out all the roots o the weedy plants. Weeds may not be a problem inthe second season, depending on the variety andtenacity o weeds present. In the third year andbeyond, the grasses, sedges, rushes, shrubs, trees,and wildfowers will begin to mature and shouldout-compete most o the weeds. Weeding isolatedpatches might still be necessary on occasion.

Be sure to maintain the rain garden plants inwhatever ashion satis es you the mostas awild-looking garden, a more manicured space,or something in between. Plants may need to bepruned as appropriate or the look you desire inyour garden.

Maintain the organic mulch layer in your rain gar-den by replenishing it when needed. Apply mulch

Figure 28: A rain garden that is mulched with gravel rather than bark.(Photo: Portland BES)

Figure 29: Gravel, rocks, and even driftwood add to the interest in this raingarden. The pea gravel also acts as mulch, helping to retain soil moisture while atthe same time minimizing erosion.(Photo: Robert Emanuel, OSU)

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to a 2-inch depth on bare soil. I your rain gardenreceives any sediment or soil eroded rom other

locations in your landscape, you may need to cleanthis out on occasion. It is important also to keepexposed the rocks, tiles, or other hard sur aces youplaced in the rain garden to slow water at the infowand outfow points, so that they can continue toslow down water and prevent erosion.

Depending upon the local climate and plant choice,plants may need supplemental water during thesummer. This is especially true in eastern, cen-tral, and southern Oregon. The use o native anddrought-tolerant plants will help reduce the amounto supplemental irrigation during dry periods.

Figure 30 (above): A newly established rain garden in Gresham, Oregon (Photo: City of Gresham).

Figure 31 (right):This Willamette Valley rain gardenis planted with Autumn Joy Sedum(Sedumtelephium) , slough sedge(Carex obnupta) , NewZealand sedge(Carex testacea) , yellow-eyed grass(Sisyrinchium cali ornicum)and mallow (Malva spp.) .(Photo: Chris LaBelle, OSU)

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Dont drown your plants!Another consideration is to make sure your plantsin the base dont drown in their rst winter. Plantsneed air in the soil, so when the rain garden staysconsistently fooded or long, wet winters, it maybecome necessary to notch the berm at the outletto a lower elevation or add more notches to theberm. This will help the rain garden drain a little

aster and give the plants a chance to establishhealthy roots. A ter the rst winter, ll in the notch-es and allow it to unction normally. Some pro es-sionals and gardeners even advocate divertingstormwater rom the rain garden or the rst year ortwo while plants become established, especially inheavy soils.

A note about Oregons regionsOregon is a much more geographically diverse statethan most. Climates and soils can vary signi cantlybetween the coast, Willamette Valley, Cascades,eastern high desert, and southwestern mountains.Below are a ew tips on region-speci c items to beaware o in designing, building, or maintaining arain garden.

Willamette Valley:Most o the materialsincluding many o the plantselections in this guidewill help rain gardenersin the Willamette Valley. With its generally mildseasons, good soils, and mostly fat territory, theWillamette Valley presents ew obstacles or raingardeners. When planning your rain garden or theWillamette Valley, keep these things in mind: Summertime temperatures can occasionally

exceed 90 degrees; thus, some plants in sunnylocations with ast-draining soils will need supple-mental irrigationat least or the rst two orthree years while roots are becoming established.

Wintertime temperatures in some locations candrop well below reezing and thus create prob-lems or more tender or sensitive plants. It is

important to choose plants adapted to both sum-mer and winter conditions in your area.

The Willamette Valley contains the states biggestcities, each o which may have their own require-ments or on-site stormwater management(and rain gardens). I you live in Salem, Eugene,Gresham, or Portland, contact your local govern-ment or more in ormation.

Coastal Oregon:With the infuence o strong Paci c winds, abun-

dant rain all, and generally milder temperatures, thecoast can be challenging or rain gardeners but alsopresents some great opportunities. When planningyour rain garden on the coast, keep these things inmind: Strong winds can dry out and damage plants any

time o the year, especially or gardens locatednear the beach. Provide or shelter, or plan yourplant selections to take account o the wind dam-age. Additional water may be necessary during

Figure 32:A rain garden in Portland, Oregon.(Photo: Portland BES)

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the summer months, when drying winds can bemost damaging or newly established rain gardenplants.

On the Oregon coast, rain all is very abundant.Where coastal soils drain at less than 1 1/2 inchesper hour, size the rain garden to at least 15percent o the impervious sur ace. For example,a rain garden is designed to capture runo roma 300-square- oot sur ace. Hence, the calcula-tion is 300 x .15 = a 45-square- oot rain garden.Consult our online materials at extension.oregonstate.edu/watershed/rain-gardens ormore in ormation on using the modelingmethod to size your rain garden or your soiland precipitation.

Some beach homes are built on ossilized sanddunes. Soils on and around these geologic ea-tures will drain extremely rapidly, o ten in excesso 2 inches per hour, making a rain garden unnec-essary or impractical. Furthermore, the additionalwater rom a rain garden built on a ossilizeddune may cause it to slump or even collapse. Wedo not recommend constructing a rain gardenunder these conditions.

Southwestern, central, and easternOregon:Gardening in southwestern, central, or easternOregon can be rewarding but has its own set o challenges. These arid and semi-desert regions arecharacterized by volcanic, rocky, or clay soils, andsteep slopes. And i that isnt enough, many gar-deners must balance these restrictions with hungrydeer and the reality o living in a wild re-prone area.

When planning your rain garden or either region,keep these actors in mind: I you live in a re-prone area, avoid using plants

in your rain garden that are fammable. Plantswith dry material (such as leaves or needles)and those with ne structure, aromatic leaves,loose bark, or resinous sap tend to be fammable.Consult the Extension publication Fire-ResistantPlants for Oregon Home Landscapes or morein ormation and a list o re-resistant plants(available online at extension.oregonstate.edu/

emergency/FireResPlants.pd or by visiting yourlocal OSU Extension Service o ce).

These semi-arid regions have long, dry summerswith very little rain all. Depending on your plantchoice, it may be necessary to irrigate your raingarden two to three times each summer to keepthe plants healthy, attractive, and re-resistant.

I deer plague your garden, use rain garden plantsthat are also deer-resistant. Although ew plants

are truly deer-resistant in every situation, mostnurseries can provide a list o plants that deertend to avoid.

Central and eastern Oregon winters are longerand colder than in other areas o Oregon. Plantsmay not establish new roots well in rozen soils.Plan to construct and plant your garden earlyenough in the late summer to allow or plantsto become established. Native plants that canhandle the annual swings in temperature willsurvive best in a low-care rain garden.

I you live in a location with ast-draining volcanicsoils, you might want to make your rain gardenshallower or smaller, depending on your spaceconstraints or needs. Consult our online materi-als at extension.oregonstate.edu/watershed/rain-gardens or more in ormation on using themodeling method to size your rain garden oryour soil and precipitation.

Figure 33:Rain garden at Astor Elementary School in Portland, OR. (Photo: Candace Stoughton, EMSWCD)

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yr SS

gr

dr

pc

Os

Dr

Ds

cr

Gc

Drlp

CENTRAL OREGON SUNAbbr. Common name Scientifc name Qty.

SS Smooth sumac Rhus glabra 1Ds Douglas spiraea Spiraea douglasii 3Dr Dwar redtwig dogwood Cornus sericeaKelseyi 11Gc Golden currant Ribes aureum 1Os Oceanspray Holodiscus discolor 1gr Canada goldenrod Solidago canadensis 13cr Common rush Juncus effusus var. paci cus22dr Dagger-lea rush Juncus ensifolius 13lp Large-lea lupine Lupinus polyphyllus 13pc Purple conefower Echinacea purpurea 6yr Yarrow Achillea millefolium 9

Sample Rain Garden Layouts

These sample rain garden layouts use plants suitableor the states di erent regions. Consider whether

you want your garden to be ormal, in ormal, roundor square. Use these designs to give you ideas orhow to incorporate di erent types o plants into thewetter and drier zones o your rain garden.

The abbreviations used will help you see at a glancewhich type o plant is being re erenced. Two capitalletters denote a tree; a capital and lower-case com-bination denotes a shrub; and two lower-case lettersmean the plant is a perennial, rush, sedge, or grass.

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NBcr

Dr

Tg

wf

SuBh

th

Dr

Mo

wf

CENTRAL OREGON SHADEAbbr. Common name Scientifc name Qty.

NB Paci c ninebark Physocarpus capitatus 1Bh Black huckleberry Gaylussacia baccata 4Dr Dwar redtwig dogwood Cornus sericeaKelseyi 8Su Gro-low sumac Rhus aromatica Gro Low 1Mo Mock orange Philadelphus lewisii 1Tg Tall Oregon grape Mahonia aquifolium 3cr Common rush Juncus effusus var. paci cus 13th Tu ted hairgrass Deschampsia caespitosa 20w Western escue Festuca occidentalis 10


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yr

sr

Tg

Fc

nzNr

Tg

yr

th

PC

sr


SOUTHWEST OREGON SUNAbbr. Common name Scientifc name Qty.

PC Paci c crabapple Malus fusca 1Fc Flowering currant Ribes sanguineum 3Nr Nootka rose Rosa nutkana 3Tg Tall Oregon grape Mahonia aquifolium 6nz New Zealand sedge Carex testacea 14sr Spreading rush Juncus patens 6th Tu ted hairgrass Deschampsia caespitosa 8yr Yarrow Achillea millefolium 12

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SOUTHWEST OREGON SHADEAbbr. Common name Scientifc name Qty.

CA Cascara Rhamnus purshiana 1Bt Black twinberry Lonicera involucrata 6Eh Evergreen huckleberry Vaccinium ovatum 8Nr Nootka rose Rosa nutkana 6Tg Tall Oregon grape Mahonia aquifolium 2lp Large-lea lupine Lupinus polyphyllus 2sb Santa Barbara sedge Carex barbarae 16wg Wild ginger Asarum caudatum 12


Eh

CA

Eh

sb

lp

wg

Tg

Nr

Tg

wg

BtBt

lp

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WILLAMETTE VALLEY SUNAbbr. Common name Scientifc name Qty.

SA Sitka alder Alnus viridis ssp. sinuata 1Bh Baldhip rose Rosa gymnocarpa 6Ro Red osier dogwood Cornus sericea 3Rm Rosemary Rosemarinus of cianalis 4dr Dagger-lea rush Juncus ensifolius 25tt Taper-tipped rush Juncus acuminatus 10w Western escue Festuca occidentalis 6


Rm

wf

Ro

SA

tt

Bh

dr

Bh

Bh Bh

Bh

wf

Ro

Ro

RmRm

Bh

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WILLAMETTE VALLEY SHADEAbbr. Common name Scientifc name Qty.

VM Vine maple Acer circinatum 1Dg Dull Oregon grape Mahonia nervosa 14Dr Dwar redtwig dogwood Cornus sericeaKelseyi 9Sb Snowberry Symphoricarpus alba 3ds Dense sedge Carex densa 13br Small- ruited bulrush Scirpus microcarpus 11


Dg

Dr

br

Sb

ds

Dg

VM

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OREGON COAST SUNAbbr. Common name Scientifc name Qty.

PW Paci c willow Salix lucida ssp. lasiandra 1Es Dwar escallonia EscalloniaNewport Dwar 4St Silktassel Garrya elliptica 1cs Curly sedge Carex rupestris 32oi Oregon iris Iris tenax 11sl Spanish lavender Lavandula stoechas 13s Sword ern Polystichum munitum 3


cs

Essl

sl

St sf

oi Es

PW

oi

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OREGON COAST SHADEAbbr. Common name Scientifc name Qty.

IP Indian plum Oemleria cerasiformis 1Bb Blue-ridge blueberry Vaccinium pallidum 3Cl Common lilac Syringa vulgaris 1Dr Dwar redtwig dogwood Cornus sericeaKelseyi 6cr Common rush Juncus effusus var. paci cus 8bh Paci c bleeding heart Dicentra formosa 13ss Slough sedge Carex obnupta 13s Sword ern Polystichum munitum 6


Bb

bhIP cr

Dr

ss

bh

bh

Clsf

sf

Dr

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Rain Garden Plant List: Trees and Shrubs

C o m m

o n N

a m e

S c i e n t

i f c N a m e

O r e g o n

N a t i v e

W i l l a m e t

t e V a l

l e y

C o a s t

C e n

t r a l

/ E a s

t

S o u

t h w e s t

M o i s t u r e

Z o n e

S u n

R e q u i r e m e n

t s

H e i g h

t

W i d t h

P l a

n t

C h

a r a c

t e r i s

t i c s

Vine maple Acer circinatum Y X X X X

moderate,dry

shade/part 1520' 1520'

Small, multi-stemmed tree,red-orange all color,excellent soil binder

Sitka alder Alnus viridis ssp.sinuata

Y X X X wet,moderate ull/shade 315' 1015' Fixes nitrogen in soil

Red osier dogwood Cornus sericea

Y X X X Xwet,

moderate,dry

ull/part 48' 48'Red twigs provide winterinterest, white fowers insummer

Dwarf redtwig

dogwood Cornus sericeaKelseyi

Y X X X Xwet,

moderate,dry

shade/ull 2' 2'Red twigs provide winterinterest, white fowers insummer

Dwarf escalloniaEscalloniaNewport Dwar

N X X X moderate,dry part 3' 4'Evergreen, fowers in latesummer, ragrant

Silktassel Garrya elliptica Y X X dry ull 612' 612'

Evergreen, fowers in spring,berries attract wildli e

Blackhuckleberry Gaylussaciabaccata

N X Xwet,

moderate,dry

shade/ull 13' 3'

Flowers in summer, edibleberries, likes acidic soil

The Oregon Rain Garden Guide: Landscaping for Clean Water and Healthy Streams36

TREES AND SHRUBS

J i m P o l l o c k

B r e n t

M i l l e r

LindaMcMahan ,

O S U E x t e n s

i o n

T e r e s a

H u n t s i n g e r

R e b e c c a

G e b e s

h u b e r

P e t e V e i l l e u x

M a r

i e l l e A n z e l o n e

See page 20 for tips on choosing rain garden plants. Note that plant size will vary by location.Consult your nursery or OSU Extension Service of ce for locally accurate size information.

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C o m m

o n

N a m e

S c i e n t

i f c

N a m e

O r e g o n

N a t

i v e

W i l l a m e t

t e V a l

l e y

C o a s t

C e n

t r a l

/ E a s

t

S o u

t h w e s

t

M o i s t u r e

Z o n e

S u n

R e q u i r e m e n

t s

H e i g h

t

W i d t h

P l a

n t

C h a

r a c t e r

i s t i c s

Ocean sprayHolodiscusdiscolor

Y X X X X moderate,dry ull/part 48' 36'Flowers in summer,attractive to wildli e, goodsoil binder

Spanish lavendar Lavandulastoechas

N X X X moderate,dry ull 1' 12'Evergreen, pleasant

ragrance, attractive summefowers

Black twinberryLonicerainvolucrata

Y X X X X wet,moderate part 7' 10'

Yellow fowers in summer,

black berries with bright redbracts, attractive tohummingbirds

Tall OregongrapeMahoniaaquifolium

Y X X X X moderate,dry ull/part 4' 4'Evergreen, yellow fowers inspring, bronze all color

Dull Oregon

grapeMahonia nervosa

Y X X X Xmoderate,

dryshade/

part 2' 2'Evergreen, yellow fowers inspring, berries attract wildli

Paci c crabappleMalus fusca Y X X X

wet,moderate ull/part

1030'

1030'

Flowers in spring, attractiveto wildli e

Indian plum

Oemleriacerasiformis Y X X X

wet,

moderate,dry part 10' 5'

Flowers very early spring,

ragrant leaves, suckeringhabit

Mock orangePhiladelphuslewisii

Y X X X X moderate,dry part 5' 3'Fragrant fowers attractbirds, butterfies, and bees,prune to shape

3The Oregon Rain Garden Guide: Landscaping for Clean Water and Healthy Streams

Trees and Shrubs

M . S . Y

a m a s a k

i

E d d R u s s e l l

K a r e n

H a a r d

S t e v e

M a t s o n

M a t e

A d a m

k o v i c s



a r r o w

l a k e l a s s

@ f i c k r

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C o m m

o n

N a m e

S c i e n t

i f c

N a m e

O r e g o n

N a t

i v e

W i l l a m e t

t e V a l

l e y

C o a s t

C e n

t r a l

/ E a s

t

S o u

t h w e s

t

M o i s t u r e

Z o n e

S u n

R e q u i r e m e n

t s

H e i g h

t

W i d t h

P l a

n t

C h a

r a c t e r

i s t i c s

Paci c NinebarkPhysocarpuscapitatus

Y X X X X wet,moderate ull/part 613' 613' Unique shredding bark,drought tolerant

CascaraRhamnuspurshiana

Y X X X moderate shade/ull to 20' to 15'Shrub or small tree, yellow

all color

Grolow sumacRhus aromaticaGro Low

N X X moderate,dry ull/part 2' 68' Fragrant, orange-red allcolor

Smooth sumacRhus glabra Y X X X X dry

shade/ull 612' 10'

Orange-red all color,suckering habit

Golden currantRibes aureum Y X X

wet,moderate ull 68' 68'

Frangrant spring fowers,edible ruits

FloweringcurrantRibes sanguineum

Y X X Xwet,

moderate,dry

ull/part 10' 7' Showy, pink fower clustersin spring, attractive to birds

Baldhip roseRosa gymnocarpa Y X X X X

wet,

moderate,dry ull/part 23' 3' Flowers in summer

Nootka roseRosa nutkana Y X X X X

wet,moderate,

dry

shade/ull 5' 5'

Large, ragrant, showyfowers in late spring, bewareo thorns

Trees and Shrubs


D o u g

W a y

l e t t

LindaMcMahan,

O S U E x t e n s

i o n



PortlandBureauo

E n v i r o n m e n

t a l S e r v i c e s

K a r l i

S c o t

t

J o h n H a g s t r o m

LindaMcMahan,

O S U E x t e n s

i o n

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C o m m

o n

N a m e

S c i e n t

i f c

N a m e

O r e g o n

N a t

i v e

W i l l a m e t

t e V a l

l e y

C o a s t

C e n

t r a l

/ E a s

t

S o u

t h w e s

t

M o i s t u r e

Z o n e

S u n

R e q u i r e m e n

t s

H e i g h

t

W i d t h

P l a

n t

C h a

r a c t e r

i s t i c s

RosemaryRosmarinusof cianlis

Y X X X dry ull 3' 3'Evergreen, fowering beginsin winter, resh or driedleaves used in cooking

Paci c willowSalix lucida ssp.lasiandra

Y X X X X wet,moderate ull 13' 10'Male and emale catkins areborne on separate plants

Douglas spirea/hardhackSpirea douglasii

Y X X X Xwet,

moderate,dry

ull/part 5' 5' Pinkish fower clusters insummer

SnowberrySymphoricarpusalba

Y X X X X moderate,dryshade/

ull 6' 4'Flowers in spring, whiteberries provide winterinterest, excellent soil binde

Common lilacSyringa vulgaris N X X X

moderate,dry ull/part 15' 612'

Showy, ragrant lavenderfowers in late spring

EvergreenhuckleberryVacciniumovatum

Y X X X moderate,dry part to 9' to 8'

Evergreen, edible berries inlate summer, new growthemerges bronze in color,requires acidic soil, prune toshape

Blue ridgeblueberryVacciniumpallidum

N X Xmoderate,

dryshade/

ull 23' 23' Edible berries

Trees and Shrubs

The Oregon Rain Garden Guide: Landscaping for Clean Water and Healthy Streams 3

NOTES:

OregonEnvironmental

C o u n c

i l

N e wY o rkB ot a ni c al

G a r

d e n

O S U E x t e n s

i o n

B r u c e

M . M

a r s h a l

l

N e a

l K r a m e r

O S U E x t e n s i o n

V i c t o r F a r

i n e l l i

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C o m m

o n N

a m e

S c i e n t

i f c N a m e

O r e g o n

N a t i v e

W i l l a m e t

t e V a l

l e y

C o a s t

C e n

t r a l

/ E a s

t

S o u

t h w e s t

M o i s t u r e

Z o n e

S u n

R e q u i r e m e n

t s

H e i g h

t

W i d t h

P l a

n t

C h

a r a c

t e r i s

t i c s

Yarrow Achilleamillefolium

Y X X X X moderate,dry ull 2' 2'Summer fowers,spreads by rhizomes

Wild ginger Asarumcaudatum

Y X X X X moderate shade/part 10" spreading Evergreen, pleasantragrance

Paci c bleedingheartDicentra formosa

Y X X X X moderate,dryshade/

part 2' 2'Delicate oliage withattractive spring fowers

Purple

cone ower Echinaceapurpurea

N X X X X moderate,dry ull 3' 2' Summer fowers,attractive to wildli e

Oregon irisIris tenax Y X X X

wet,moderate,

dryull 1' spreading

Evergreen, grassyoliage, showy spring

fowers

Large-leavedlupineLupinuspolyphyllus

Y X X X Xmoderate,

dry ull/part 3' 2'Showy spring fowers,

xes nitrogen

Sword fernPolystichummunitum

Y X X X moderate shade/ull 3' 3'Shiny, leathery,evergreen leaves

Rain Garden Plant List: Perennials

PERENNIALS


J o r d a n

M e e t e r

O S U E x t e n s

i o n

J o n

S u l l i v a n


O S U E x t e n s

i o n

M i c h a e l

G . S h

e p a r

d

F r a n s

S c h m i t

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C o m m

o n

N a m e

S c i e n t

i f c

N a m e

O r e g o n

N a t

i v e

W i l l a m e t

t e V a l

l e y

C o a s t

C e n

t r a l

/ E a s

t

S o u

t h w e s

t

M o i s t u r e

Z o n e

S u n

R e q u i r e m e n

t s

H e i g h

t

W i d t h

P l a

n t

C h a

r a c t e r

i s t i c s

Canada

GoldenrodSolidagocanadensis

Y X X X X moderate,dry ull 3' 2' Pyramidal fower clustersin late summer

Santa Barbarasedge Carex barbarae

Y X wet,moderate ull/part 13' spreading Evergreen, fowers insummer

Dense sedgeCarex densa Y X X X

wet,moderate

shade/ull 2' spreading

Evergreen, good orerosion control, trappingsediment and slowing thefow o water

Slough sedgeCarex obnupta Y X X X X wet ull/part 25' spreading Excellent soil binde

Curly sedgeCarex rupestris N X X X wet

shade/ull 14" spreading Evergreen

Orange New

Zealand sedgeCarex testacea N X X Xwet,

moderate ull 25' 1'

Light green leaves

develop red/orangehighlights

Tufted hair grassDeschampsiacaespitosa

Y X X X X wet,moderate ull/part 2' 3'Attractive throughoutwinter

Perennials

RUSHES, SEDGES, AND GR ASSES

4The Oregon Rain Garden Guide: Landscaping for Clean Water and Healthy Streams

M a r

t i n V a v r

k

C l a u d

i a V i e i r a


P a t r i c k S t a n

d i s h

Dr.DeanWm.Taylor,

J e p s o n

H e r

b a r i u m



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Rushes, Sedges, and Grasses

C o m m

o n

N a m e

S c i e n t i f c

N a m e

O r e g o n

N a t

i v e

W i l l a m e t

t e V a l

l e y

C o a s t

C e n

t r a l / E a s t

S o u

t h w e s

t

M o i s t u r e

Z o n e

S u n

R e q u i r e m e n

t s

H e i g h t

W i d t h

P l a

n t

C h a

r a c t e r i s t

i c s

Western fescueFestucaoccidentalis

Y X X X X moderate,dry part 13' 13'Inconspicuous yellowfowers and brown seeds.Short-lived (20 years)

Taper-tippedrush Juncusacuminatus

Y X X X X wet ull/part 3' spreading Drought tolerant

Common rush Juncus effususvar. paci cus

Y X X X X wet,moderate ull/part 35' spreading

Tolerant o pollutedconditions. Note thatEuropean so t rush ( J.effusus var. effusus) canbe invasive. Please usethe native Paci c variety

Dagger-leaf rush Juncus ensifolius Y X X X X wet ull/part 2' spreading

Flattened stems muchlike an iris

Spreading rush Juncus patens Y X X X X wet ull/part 2' spreading Bluish-green oliag

Small-fruitedbulrushScirpusmicrocarpus

Y X X X X wet ull/part 4' spreading Good soil binder


S t e v e M a t s o n

PortlandBureauo

E n v i r o n m e n


D e n

i s B o u s q u e

t

K e i r M o r s e

RobertH.Mohlenbrock,

U S D A N

R C S

PortlandBureauo

E n v i r o n m e n


NOTES:

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For more in ormation:OSU Water and Watershed Education:extension.oregonstate.edu/watershed/rain-gardens

East Multnomah Soil and Water ConservationDistrict: www.emswcd.org

Jackson Soil and Water Conservation District:www.jswcd.org

Oregon Environmental Council:www.oeconline.org/stormwater

Andreoletti, Jessica. 2008. The Vermont RainGarden Manual: Gardening to Absorb theStorm. Winooski Natural Resources Conser-vation District. www.vacd.org/winooski/winooski_raingarden.shtml

Bannerman, Roger, and Ellen Considine.2003. Rain Gardens: A How-to Manual for Homeowners.UWEX Publication GWQ0371-06-5M-100-S. University o Wisconsin Exten-sion. clean-water.uwex.edu/pubs/pd /home.rgmanual.pd

Dunnett, Nigel, and Andy Clayden. 2007. RainGardens: Sustainable Rainwater Management

or the Garden and Designed Landscape.Timber Press.

Giacalone, Katie 2008. Rain Gardens: A RainGarden Manual for South Carolina. CarolinaCLEAR, Clemson University Public Service.www.clemson.edu/public/carolinaclear/

Hinman, Curtis. 2008. Rain Garden Hand-book for Western Washington Homeowners. Washington State University Extension.www.pierce.wsu.edu/Water_Quality/LID/Raingarden_handbook.pd

Figure 34:Rain garden using a grassy swale as the base.(Photo: Candace Stoughton, EMSWCD)

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Oregon Sea GrantCorvallis, OregonORESU-H-10-001

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