Saturday, April 11

Planning a rain garden

The lawn has a low spot, near the garage, where water collects every year. The garage in the distance does not currently have gutters, but, in the future, downspouts could be routed to feed runoff to this area, providing sufficient water for a rain garden. This would also avoid the problem of getting the lawn tractor stuck in boggy soil when trying to mow the area.

Conveniently, one of my garden magazines (Garden Gate)came recently with an article on planting rain gardens. Given the amount of stone we have freely available, a dry streambed lined with pond liner and rocks would be quite easy from the corner of the garage, as discussed in the article. It would look a lot more natural in this case than burying drain tile, since the bed floods completely and the area to the downspout would be pretty soggy as well.

The article in the magazine lists several plants that are suitable for rain gardens, but a bit of internet searching turned up this site with an excel spreadsheet of hundreds of species to choose from. There are also many other sites that will sort by zone, foliage, etc.

The plan for this site, which may not be implemented until next year, is to dig a level pit about 8 inches deep, with a berm on the near side to contain the water (sloping gradually back into the lawn such that the lawn tractor can handle it). Then filling the garden with native Wisconsin grasses and flowers, taking care not to put in anything too invasive. The border of the garden will be something that can handle occasional lawnmower hits, probably a low clumping grass. A dry streambed will carry water from the garage downspout (when it is installed), and a bridge of some sort will allow for foot traffic across to the garden from the garage. Tractor traffic will have to go around. A wide space will be left to surround the garden, to accomodate the tractor.

Of course, the WI DNR has a very helpful page on rain gardens, and a list of native plants suitable for wetlands:
Scientific Name Common Name Height Color Blooming Specialties
Zizia aurea divided golden Alexander 1-2 ft yellow May-Jun Butterflies
Solidago riddellii Riddell's goldenrod 1-3 ft yellow Aug-Oct Butterflies, Birds - Forbs
Iris shrevei wild iris 1-3 ft purple/yellow May-Jul Birds - Forbs, Hummingbirds
Chelone glabra turtlehead 1-3 ft white Jul-Sep Butterflies
Lobelia siphilitica great blue lobelia 1-4 ft blue Apr-Sep Butterflies
Verbena hastata blue vervain 2-4 ft purple Jul-Oct Butterflies
Lobelia cardinalis cardinal flower 2-4 ft scarlet Jul-Sep Butterflies, Hummingbirds
Helenium autumnale sneezeweed 2-4 ft yellow Aug-Oct Birds - Forbs
Spiraea alba meadowsweet 2-5 ft white Jun-Sep Butterflies
Eupatorium maculatum spotted Joe Pye 2-6 ft pink Jul-Sep Butterflies
Asclepias incarnata red milkweed 2-8 ft magenta Jul-Aug Butterflies
Vernonia fasciculata ironweed 3-5 ft royal purple Jul-Sep Butterflies
Cassia hebecarpa wild senna 3-6 ft yellow Jul-Aug Birds - Forbs
Epilobium angustifolium fireweed 3-7 ft pink/red Jun-Sep Birds - Forbs, Hummingbirds

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