By Patrice Peltier
Chicagoland Gardening Editor Carolyn Ulrich swore the magazine wouldn’t run an article about rain gardens until she’d seen a beautiful one. She stood her ground staunchly – some might say stubbornly – for years. Two years ago, on a trip to Olbrich Botanical Gardens in Madison, Wisc., she discovered not just one, but three, lovely rain gardens. So here, at last, is the rain garden article.
It’s not that Ulrich hasn’t long admired the intent of rain gardens: to create a landscaped basin where rainwater running off impervious surfaces can gently seep back into the earth instead of rushing into the storm sewer, picking up pollutants along the way. It’s just that more often than not, despite our best intentions, rain gardens end up a wild and weedy, kidney-bean-shaped mess at the end of a downspout, without any relationship to the surrounding landscape or the house itself.
Jeff Epping, Olbrich’s director of horticulture, agrees wholeheartedly. Too often, rain gardens look like “a pothole in the bluegrass,” he says. Always looking for ways that the botanical gardens can inspire and educate its visitors, Epping set out to show us how attractive rain gardens can be.
Rain gardens often include native prairie plants whose long roots help direct water deep into the ground. Epping uses native plants extensively, but that’s not his only – or even his primary – criteria. “Design a rain garden as you would any other perennial border,” he recommends. “Select plants based on their ornamental qualities – flower and foliage color, form, texture, size and seasonal interest.”
Some of his favorite ornamental rain garden plants include Joe-Pye weed (Eupatorium purpureum – recently renamed Eutrochium purpureum), swamp milkweed (Asclepias incarnata), great blue lobelia (Lobelia siphilitica) and cardinal flower (Lobelia cardinalis).
In fact, rain gardens expand your plant palette, Epping says. “If you have a low spot on your property or a place that’s often wet, why not put in a rain garden and take advantage of that? There are so many cool plants that like moist soils, like astilbe, ligularia and filipendula.”
Right plant, right place takes on special importance in a rain garden. Here, plants must be able to tolerate both periodic flooding and drought. Rain gardens are depressions with gently sloping sides. Often they are bermed to help retain water. They aren’t intended to have standing water for long periods of time, but the plants at the bottom of the rain garden must be able to tolerate wet soils and even submersion.
Olbrich’s rain garden next to the herb garden occasionally fills to the top. It usually drains within three days, Epping says. The bottom of this rain garden is planted with moisture-loving plants such as dark-green bulrush (Scirpus atrovirens), sweet flag (Acorus calamus), tufted sedge (Carex elata) as well as the more ornamental swamp milkweed, great blue lobelia and cardinal flower. Towards the top, Epping has added other plants that prefer to keep their feet drier such as blue vervain (Verbena hastata), foxglove beard-tongue (Penstemon digitalis) and turtlehead (Chelone glabra).
A master of the mixed border, Epping likes to add woody plants to his rain gardens. “Trees and shrubs add year-round structure as well as beauty in every season through their foliage, flowers, fruit, bark and form,” he explains. “If your garden has only perennials, when you cut them back in fall, you have nothing to look at for the rest of the year.”
Red-twig dogwood (Epping likes Cornus sanguinea ‘Cato’) and elderberry (Sambucus nigra) can handle the wetter levels of the rain garden. Higher up, Epping likes to incorporate hydrangeas, arborvitae (he likes the narrow, columnar ‘Hetz Wintergreen’) and witch hazel (Hamamelis vernalis) along the perimeter.
During a recent garden tour in Missouri, Epping discovered that red buckeye (Aesculus pavia) grows along streams there. Already a fan of this small tree’s showy panicles of red tubular flowers, Epping is eager to incorporate more of these into Olbrich’s rain gardens.
Epping also likes to incorporate bulbs in all his gardens – and the rain gardens are no exception. He plants camassia lower in the rain garden because it’s one of the few bulbs that can tolerate wet conditions. Near the perimeter, he plants narcissus and Anemone blanda for early-season color.
“It’s important to make a rain garden feel like it’s part of your overall landscape. It should work seamlessly with the landscape around it,” Epping suggests. For instance, one of Olbrich’s rain gardens borders the rose garden. There, Epping has repeated roses, daylilies, salvia and Stachys monieri ‘Hummelo’ – all plants used in the rose garden – along the perimeter of the rain garden. In the rain garden next to the herb garden, he’s incorporated a variety of herbs.
Finally, Epping says, if you want your rain garden to be beautiful, “Remember, it is like any other garden. It needs maintenance.”
Rain gardens are a great way you can contribute to improving the water quality in your community. They can intercept much of the rainwater that pours off your roof and paved surfaces and channel it back into the ground where it helps recharge the aquifers. By capturing runoff before it reaches the storm sewer, rain gardens also help keep pollutants such as landscape chemicals and debris out of the water supply.
Rain gardens can even help manage local flooding issues.
All those benefits can make a lovely impact on our environment. Now, thanks to Olbrich, even Carolyn Ulrich has to concede rain gardens can be a thing of beauty, too.
Patrice Peltier is a freelance writer in southern Wisconsin who loves getting to visit other people’s gardens.