Using Grasses and their Look Alikes in the Shade
At one time my small, shady urban garden had a full complement of traditional shade plants like hostas, astilbe, ferns and a wide variety of other perennials that favor shade but no ornamental grasses. The only grass around was the two small patches of lawn in the front and back yard. I didn't have any garden grasses because I was afraid they would be high maintenance in the shade and too large for the garden besides. But I have learned that many ornamental grasses can handle or even prefer a bit of shade. So now I am beginning to try some grass and grass-like plants and I like what I see.
A six year study done at the University of Minnesota's Landscape Arboretum found 85 species and cultivars of ornamental grasses and their relatives that could survive in zone 4. They published the results as the bulletin,Ornamental Grasses for Cold Climates. This bulletin is available from the Minnesota Extension Service. It even gives lists of the best uses of these plants and I have been using their "Shady Locations" list.
The most useful ones for my small garden are the sedges (Carex). I have a three year old clump of Carex nigra that arches and drapes like a maiden's hair. The leaf blades are less than and quarter inch wide and the color is like a good Colorado blue spruce. In Rick Darke's wonderful Color Encyclopedia of Ornamental Grasses he says that the native American version of this plant forms "dense tussocks", so mine must be native. Apparently the European version runs. My original 4" potted plant has become about an 8" clump now. It is growing in the high shade of an old burr oak. While this plant can grow in bogs, my soil is sandy and only moist if I make it so. My plant is about a foot high, and gets to about two feet when it blooms. The flowers are interesting, but not showy. I usually cut them off when they begin to look tattered.
I also have a variegated creeping broad-leafed sedge (C. siderosticha'Variegata') that was not tested by the University and is listed by Darke as hardy only to zone 6. It has come through the last two winters in my zone 5 microclimate with leaf cover, but I think Minneapolis has had zone 6 winters for the last two, so I expect to lose it sometime. It is very pretty though and I might even plant it as an annual if it were readily available. It has leaves about one and a quarter inches wide that are white striped. The whole plant is about 8 inches high. I have never seen mine bloom and it is spreading slowly. It is nestled between two astilbe and, though I didn't know it at the time I planted it, sited above a tulip bulb. In spring the tulip emerges from the bare ground (the sedge isn't up yet), opens its bloom and continues to bloom while the sedge foliage arises around it. I always wish for a time-lapse camera.
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