Rain garden preserves natural
By Marty Hair
DETROIT - The grassy strip between the Piotrowskis' sidewalk
and the street used to turn into a soggy ditch that held
rainwater bound for the storm drain and the Rouge River.
This year, the area is a rain garden that absorbs and
filters water after each downpour.
"The rainwater doesn't last more than 24 hours,
which to me is saying the compost and sand are really
filtering the water" and helping some of it penetrate
the soil, says Linda Piotrowski, of Lathrup Village, Mich.
The native plants that grow on the site, attracting birds
and insects, are interesting to look at, too.
Call them rain gardens, swales or forward-thinking water
management. They're a far cry from the arrangement that
sends storm water spilling across pollution-encrusted
pavement and into pipes or retention basins before pouring
into lakes and rivers.
With rain gardens, the water seeps into the soil, as
it did before development and pavement disrupted the natural
Not ponds, not wetlands, rain gardens are quick-draining,
plant-filled shallow depressions in landscapes.
With the right soil mixture and the right plants, experts
say, rain gardens soak up and filter water within 48 hours
- well before the gardens have a chance to turn into mosquito
Fall is a good time to lay the groundwork for rain gardens,
which - drop by drop - may change how people think about
Before rain gardens, "this wonderful rain that fell
out of the sky was thought of as a waste product, not
a resource," Roger Bannerman of the Wisconsin Department
of Natural Resource recently told a Detroit-area workshop.
A watershed scientist, Bannerman says the phrase "rain
garden" wasn't even in his vocabulary a few years
ago. But since he has started experimenting with the gardens,
he has been overwhelmed by the interest in something so
simple. If enough people embrace rain gardening, Bannerman
predicts, "we're going to change how our cities look."
That's already happening in rain garden hot spots like
Madison, Wis.; Seattle, Wash; Prince George's County,
Md., and Minnesota's Twin Cities.
Rain gardens are trickling into other areas, too. Lathrup
Village has streetside ditches rather than curbs and gutters,
so rain gardens are helping to reduce the amount of standing
water, a big concern because of West Nile virus. By filtering
water and sending less of it into drains and ultimately
the Rouge, rain gardens also boost the river's water quality.
To see how a rain garden would look, the city built a
20-foot-by-40-foot model last year next to the municipal
building's parking lot. Grass wouldn't grow in the wet
"It was just a nasty-looking area" that held
the parking lot's salty runoff on its way to a drain and
the Rouge, says Jeff Mueller, assistant city administrator.
Working with the Southeastern Oakland County (Mich.)
Water Authority, city workers dug down 3 feet around the
drain, removed debris and clay soil and replaced it with
a compost-sand mix. Then volunteers and local gardeners
planted native wildflowers and shrubs like penstemon,
sweetspire and serviceberry, which can thrive with occasional
wet feet but under mostly dry conditions as well. On top,
the workers spread a layer of shredded bark mulch. Materials
A perforated pipe under the soil catches extra water;
really heavy amounts go to a sump and into the regular
storm sewer. The installation recently won a Keep Michigan
Beautiful Inc. award.
Best of all, it works.
"Even with some of these whopper rains we've had,
the garden can handle it," Mueller says. The rain
garden's success led the city and the regional water authority
this year to work with several home owners, including
Mark and Linda Piotrowski, to build rain gardens that
the home owners plant and maintain.
Elsewhere, rain gardens are becoming outdoor classrooms.
At Buchanan Elementary School in Livonia, Mich., parent
Laura Jannika and others worked with Bill Craig of the
National Wildlife Federation and students to turn a wet
mowed section near the school into a rain garden with
native plants and a dry stone riverbed. Students in all
grades take turns learning about animals and plants in
the rain garden. According to Principal Marjorie Moore,
the youngsters held a contest to name the garden. The
winner was Buchanan Oasis Garden, or BOG.
Rain gardens can fit into a bigger scheme to manage runoff.
At the University of Michigan's Nichols Arboretum in Ann
Arbor, Mich., a garden was dedicated Oct. 11 with several
stepped plantings. The installation, says arboretum director
Robert Grese, slows the water as it runs off a hill and
down toward Schoolgirls' Glen. The planting also encourages
water to absorb into the soil.
On the other side of the state, the West Michigan Environmental
Action Council is working with the City of Grand Rapids,
Kent County and other groups and businesses to build rain
gardens. Four demonstrations are in place with others
planned for 2004. Patricia Pennell plans to post several
designs for Great Lakes rain gardens on her Web site,
, but cautions that no one design fits all.
Designs must be selected for the site. A rain garden
of tall grasses looks spectacular in a rural setting but
weedy in the city.
The Piotrowskis have enjoyed their rain garden this year,
and Linda is eager to see the blue flag iris bloom next
"It really looks nice having a garden out in the
front," she says. "The softness of the garden
next to the cement is really attractive."