amanda Griesser / ahs archives Rainscaping important role in protecting the health of local watersheds. By employing a variety of techniques to keep rainwater on their properties, gardeners can play an approaches are often collectively called collectively often are approaches ening the load on our watersheds. These light- and runoff stormwater managing recommending a variety of approaches to groups throughout the United States have been environmental and planners urban decades, of couple last the Over ous surfaces than there are in rural areas. impervi- of percentage greater a is there A tributed to Joe Keyser, who was public ed- Credit for coining 1990s. the late term the is in generally region at- Mid-Atlantic “rainscaping,”a term that evolved in the nounced in our cities and suburbs, where other water bodies. in local , rivers, lakes, and source (NPS) pollution—ends up non-point as it to refer agencies contaminants—environmental products. Ultimately this cocktail of from animal waste, and petroleum bacteria salts, de-icing pesticides, fertilizers, as such contaminants runoff picks up and carries with it resulting The surfaces. pervious roads, parking lots, and other im- roofs, sidewalks, , driveways, waterways and watersheds. local our on have bors—might ing —and those of my neigh- slop- and driveway my down ran that water excess the effect what it never occurred to me to think of my plants keeping happy. for Until a few process years ago, the of rain as a natural and welcome part view I gardeners, most like And, the plants glistening with water droplets. admiring and landscape washed freshly a of aroma the in breathing downpour, still revel in the immediate aftermath of a P pluin s ot pro- most is pollution NPS When it rains, water runs off our sloshing through the puddles. I puddles. the through sloshing enjoyed I because mainly rain S A CHILD, A S I looked forward to be used to collect water for plants. downspouts,can barrels,attachedto Rain water close to the source using low-im- using source the to close water a County, “Capturing gomery Maryland. Mont- in did English, Keyser department same the in Ann works who Planner RainScapes explains ways,” pervious surfaces are on roofs and drive- im- of percent 70 about development, water for later use. “In a typical housing rain- store and divert, capture, helping by processes natural mimic Rainscapes FOR RAIN LANDSCAPING Bay Foundation.” Chesapeake nonprofit bythe developed inspired by “the catchy Bayscapes program2006. According to Keyser, the name was of Environmental Protection (DEP) until Mont- gomeryCounty, the Maryland, Department with coordinator ucation BY KRIS WETHERBEE hn en ls a rnf, sy John says runoff,” as lost being than rather use future for contained is or soil the into “More infiltrates faceted. water one’s property,” says English. enhances and runoff stormwater duces re- both techniques development pact before deciding which rainscaping tech- for-hire debate, other factors to consider quent do-it-yourself versus professional- ning are essential,” he says. plan- runoff and considerations, safety analysis, cost “Careful pavement. and pavers permeable and hardscapes, and concrete porous roofs, green installing quired for more complex projects such as re- typically are construction and ning water-harvesting water features. ating rain and constructing rain- The benefits of rainscaping are multi- Besides your budget and the conse- the and budget your Besides plan- professional that says Church footprint. and reduce a community’s carbon value, property increase habitat, a can also enhance wildlife various rainscaping techniques in ity and soil infiltration, employing well as replenish groundwater.” as and contamination, water surface erosion, streambank ing, ing runoff can help decrease flood- of Illinois University Extension Center. the “Reduc- of partment de- Management Resources ural Church,educatoran intheNat- progressive approaches such as cre- ing a canopy of trees and shrubs, to drain, digging a dryFrench a well, installing and plant-cisterns, and garden beds, setting up rain barrels to downspouts redirecting clude solutions straightforward that in- Rainscaping techniques range from WATER WORKS Besides improving water qual- July / August August / July 2010 37 niques to implement include the volume replenish water features, and irrigate If you live in a region where mosquitoes and timing of rainfall, topography of plants in containers and beds. That is, as- are a problem, you will need a mosquito- your landscape, soil porosity, and the size suming you have enough containers to proof screen on your rain barrel or cistern. of your lot and roof. Also identify any accommodate the runoff. Or you can add non-toxic products that problem areas; for instance, underground Commercial rain barrels typically kill mosquito larvae, such as Mosquito utilities could interfere with digging hold between 55 and 100 gallons and Dunks, to containers. (there’s a toll-free number you can call to come in a variety of styles and shapes. It’s have your site checked before you dig, see also fairly easy to make your own; many DRY WELLS AND FRENCH DRAINS “Resources,” page 40). Finally, decide jurisdictions sponsor rain-barrel work- A dry well is a good option when rainfall whether your goal is to divert or spread shops. While rain barrels are relatively in- is intermittent. Water enters the passive out runoff or, rather, to capture and reuse expensive and easy to install, they are, underground structure through one or it to water your landscape. almost literally, a drop in the bucket more entry pipes or channels located at Keep in mind that certain rainscaping when it comes to reducing runoff. A roof its top, and is then discharged through a practices that work well in one area may generating 300 gallons in a typical rain- number of small exit openings, where it perform poorly in another. It all depends fall would require six 55-gallon rain bar- gradually dissipates into the ground. on your site, climate, and available conditions for in- stalling each type of system. English explains that while it may be critical to create a tree canopy in some areas, installing a rain gar- den may well be the method of choice in other areas. Likewise, water harvesting that implements a “catch and release” system of cap- turing the water and slowly releasing it might be the best approach for some. In other areas where land is scarce, replacing driveways with permeable interlocking con- crete pavers is an excellent solution for reducing rain- water runoff. Regardless of where you live, there are a wide variety of rainwater management options to consider. Let’s look at some of the main ones to help you decide which ones—or Green or living roofs, such as this one at the AHS’s River Farm headquarters in Alexandria, which combinations—are right for you. Virginia, can help reduce runoff by absorbing some rainfall in the growing medium.

RAIN BARRELS AND CISTERNS rels to house that amount of water. A French drain moves surface and A roof equipped with a gutter system can The next step up is to install a cistern, groundwater from one area to the next. funnel rainwater to rain barrels or a cis- which is a super-sized water tank that can This type of system uses a perforated pipe tern. How much water you collect de- hold anywhere from 1,000 to 10,000 gal- placed in a gravel-lined trench. The pipe is pends on the size of your roof and the lons. “To really make a difference in uti- topped with a grate or filter fabric and then capacity of the cistern or rain barrels. lizing runoff, one would need to install a covered with soil. Grass is often planted on Consider that a one-inch rainfall over very sizeable cistern, or direct the excess top. Church suggests using a French drain a 1,000-square-foot roof generates about water from your rain barrel or cistern to to catch the runoff from a paved surface 620 gallons of water. If your average an- another containment feature, such as a (such as a home foundation, patio, or re- nual rainfall is 40 inches, your yearly rain garden,” note Mark Sindell and Zack taining wall) so that it can slowly spread water yield rises to nearly 25,000 gallons. Thomas, landscape architects with into the rest of the landscape. Water from That amounts to an ample supply of “on GGLO, an architectural firm in Seattle, a French drain can also be directed to a dry

the house” rainwater to fill the birdbath, Washington. well or rain garden. mary yee

38 the American Gardener

top: donna krischan. bottom: mark turner They also remove pollutants through the prove effective in regions with sandy soils. Swales provide runoff control but may not grassesor other low-growing vegetation. are covered with a dense growth of hardy a French to drain except thesimilar earthen is channels system The system. ter nativefor homes lacking a curb and gut- Agrassy or planted swale is a good alter- STRIPS FILTER AND VEGETATIVE SWALES area, slope, height and density of the grass, tential and runoff control depend on the filtering action of the plants. Filtering po- Vege system. tative collection strips help reduce water the influx surface of other or , , a and surface paved pavement, and lawns. Typically they are rooftops, from runoff stormwater duce and the quantity of flow. pollutants and sediment, but are less effec- the between situated are and edge, the parallel to pavement, at least one foot from tightly planted with grass, but they can in- tive at removing soluble pollutants. clude shrubs or other plants. The strips run Like swales, vegetative filter strips re- pavers are both functional and decorative. plants. In more formal landscapes, permeable attractivelylandscaped with moisture-loving rainfallin their gardens. Swales, top, can be Homeowners have diverse options for keeping landscape is on nearly everyone’s wish everyone’s nearly on is landscape or garden the in feature water a Having FEATURE WATER A FUNCTIONAL of a certified contractor. sential, so you may want to enlist the help sometimes more. Proper installation is es- expect up to 80 percent water infiltration, can soak through, though usually you can type of paver determines how The much concrete. water porous and fashion, like grid- in created pavers concrete locking includegrass pavers, gravel pavers, inter- also makes for great curb appeal. mer heat levels are reduced. This system are reduced, snow melts faster, and sum- pollutants of runoff surface and runoff Water system. the within voids create duced with holes or larger aggregates that through the surface. The pavers are pro- or concrete while allowing water to filter vides the strength and stability of asphalt pro- hardscaping permeable driveways, A great choice for , sidewalks, and SURFACES PAVERS AND POROUS PERMEABLE Examples of permeable paving systems July / August August / July 2010 39 list. But a water feature on its own does little to reduce stormwater runoff. At least, that used to be the case. Some newer sustainable stormwater management solutions now combine a re- circulating decorative water feature with a sub-surface rainwater harvesting collection system. The underground tank is con- nected to a high pressure pump, so you can have access to the stored water and use it to hand water or irrigate the landscape. A water feature can also be installed on top of permeable pavers, allowing them to collect the water and direct it to the stor- age system; overflow can be directed to a rain garden or allowed to slowly infiltrate into the soil. Mark Harp, owner of the Pond Store in Sumner, Washington, says that combining the aesthetics of a water feature with the environmental benefits of rainwater harvesting also can give you an emotional lift every time you see it at work. RAIN GARDENS A rain garden is a natural or artificial saucer-shaped depression in the landscape. Its primary function is to slow down runoff, store it temporarily, and release it gradually so it has time to spread out and soak in, but rain gardens also filter sedi- ment and pollutants while adding color and interest to the home landscape. The Decorative water features that recirculate rainwater stored in underground tanks, such as this soil at the bottom of the depression is often one installed by Mark Harp in Washington, are sophisticated solutions for reducing runoff. amended with a mix of organic matter, sand, and gravel to facilitate drainage. Rain gardens are typically planted with Sources hardy, non-invasive plants adapted to the region and the light exposure in the gar- Aqua Barrel, Gaithersburg, MD. (301) 253-8855. www.aquabarrel.com. den. These should include drought- and Cascata Rain Barrel, Cambridge, Ontario. (866) 476-6311. flood-tolerant selections suited to the vari- www.gardensupermart.com. able moisture conditions found in differ- Eagle Peak, Athold, ID. (877) 868-1195. www.epcontainers.net. ent sectors of the rain garden. Regional Green Culture, Lake Forest, CA. (877) 204-7336. www.greenculture.com. agencies often offer lists of plants for rain Planet Natural, Bozeman, MT. (800) 289-6656. www.planetnatural.com. gardens (for links to regional plant recom- mendations, visit the web special linked to Resources this article on the AHS website.) For tips on selecting an appropriate site for a rain 811: Call Before You Dig hotline. www.call811.com. garden, see the sidebar, opposite page. Backyard Conservation Wetland by the National Resources Conservation Service, Washington, D.C. www.nrcs.usda.gov/feature.backyard. PUTTING IT ALL TOGETHER Master Gardeners and County Cooperative Extensions—link to regional offices Once you know what works well in your through the American Horticultural Society website (www.ahs.org). area, you can combine several rainscaping Rain Gardening in the South by Helen Kraus and Anne Spafford. Eno Publishers, methods to achieve your overall goal. Hillsborough, North Carolina, 2009. English recalls one example where a rain Rain Gardens: Managing Water Sustainably in the Garden and Designed Landscape garden overflowed into a conservation by Nigel Dunnett and Andy Clayden. Timber Press, Portland, Oregon, 2007. landscape swale equipped with three dry

wells that doubled as stepping paths courtesy of mark harp

40 the American Gardener CHOOSING A SITE FOR A RAIN GARDEN

When planning a rain garden, three important factors to consider are size, location, and permeability of the soil. You’ll need a sizeable space for the rain garden and overflow area. According to University of Illinois Extension educator John Church, homeowners often designate an insufficient area for the volume of water it will col- lect or for the porosity of the soil in the given space. The depth is determined by the soil porosity while the length and width depend on how much water you want to capture. Typically, rain gardens range from three to six inches deep, but heavy clay soil may require up to a 12-inch depth.

Rain gardens offer an aesthetically pleasing way to solve stormwater management issues.

Before deciding on a site, check the soil to be sure that it drains adequately. One way to do this is to dig a hole 12 to 18 inches deep and fill it with water. Allow the water to drain, fill it again, and then measure the depth of the water and how long it takes to drain. “This will give you an approximation of the infiltration rate in inches per hour,” say landscape architects Mark Sindell and Zack Thomas. Soil that drains faster than one inch per hour is ideal; if it drains at a rate less than a quar- ter inch per hour, you may want to select a different location. Dry streambeds such as the one in Tucson, In Rain Gardening in the South (see “Resources,” opposite page), authors He- Arizona, top, provide a way to channel and len Kraus and Anne Spafford note that to be effective as a pollution filter, a rain slow down stormwater. Green bulrush garden’s volume (depth  length  width) should be between five and 10 percent (Scirpus atrovirens), above, irises, and many of the impervious area (rooftop and driveway, for instance) that drains into it. The other water-loving plants are good choices garden also needs to be able to drain in two to three days. for rain gardens in temperate regions. Rain gardens should be located at least 10 feet from the house, away from septic systems, wells, and underground utilities. Be sure to site them downhill of your home through the swale. She says that the com- or other structures. Avoid existing low, moist spots, which are probably better suited bination of the techniques allowed the for consideration as a . If you have a steeply sloping property or get a high homeowner to reduce not only the runoff volume of stormwater, consult a licensed landscape architect for advice. —K.W. on his property, but that of two neighbors upstream. Sindell and Thomas noted a recently tional tool used to simplify and weave to- water quality created by the alarming pace designed rain garden that incorporated gether several design elements on a tight of urbanization, suburban sprawl, and “waves” of rain garden plant masses in site,” Thomas says. habitat loss,” says Sindell. “Get inspired, varying textures and colors. Several design We can all make a difference in reduc- get out there, and do your part.” elements were incorporated into the site, ing stormwater runoff, no matter what

including an ethnobotanical urban agri- rainscaping techniques we implement in A frequent contributor to The American cultural garden and moss roof garden. our landscapes. “Even a small residential Gardener, Kris Wetherbee is a freelance

top left: karen bussolini. bottom left and riGht: courtesy “Theof jim nelson planted ‘waves’ were an organiza- rain garden helps to counter the threat to writer based in Oakland, Oregon.

July / August 2010 41