Three favourite evergreen sedges

I promised to write about native ground covers this winter and I didn’t. The thing is, if I am going to write about low-growing evergreen native plants, I have to come out as a sedge-lover, a cariceophile (sp?), and I am not sure how that admission will be received.

I know, I hear you: sedges – grassy things that for some reason aren’t grasses, and have tiny flowers of some sort, and there seems to be an unnecessary lot them.

There is a great diversity of sedges, over 200 species for the lower Great Lakes, and they do tend to be close variations on the same theme, the theme of grass-like. However….

If you have ever been walking in the woods in late winter as the snow melts and seen something that looks like a bright green patch of evergreen lawn, chances are you have seen sedges exhibiting the qualities that led me to think: I’d like that in my garden.

Carex pedunculosa is one of my favorate sedges to encounter in the woods in winter. Its leathery leaves stay a fresh, polished, deep green all winter. Its leaves are about the same width as lawn grass, and the plant grows in neat clumps about 4 or 5 inches tall. Add early yellow flower spikes that are almost showy, and what’s not to like? However, my ambition to establish this sedge as a ground cover under a redbud in my Toronto garden was not successful.

I propagated the Carex pedunculosa used in this project myself. It was not exceptionally difficult, although slow.  This is a clumping sedge, not a spreader – it must take many years to create the pretty lawns of C. pedunculosa in woods. I knew it grows on heavy, neutral soils. In fact, I collected the original seed from a woodlot that I know is on heavy clay. Once I had a few pots growing well from the seeds (two years), I was able to divide the plants gently, grow them on for another year and then plant them in the shaded spot under the redbud. Well, there were hints from the first that the site  I had chosen for them was not what they wanted. It was just too dry under the redbud, with its dense canopy, in a city garden.  They didn’t want to get close to the boxwoods – probably root competion – and then resented the heat of the early evening sunshine. I kept them going for a couple of years and then a hot summer decimated them. They died out near the trunk, near the boxwoods, and at the sunniest edge, leaving a semicircular ring of plants that just might survive but are never going to be the ground cover I wanted. Darn.

I have never seen Carex pedunculosa offered at native plant nursery, and given its slowness and exacting requirements, I cannot imagine it ever taking the horticultural world by storm. A pity, ’cause it is a handsome little thing when encountered in the woods.

Carex pedunculosa in Toronto garden.

Another sedge that I love is called Carex eburnea. This is the finest textured of the sedges in Ontario woods, where it makes the softest and most delicate of evergreen puffs and little carpets. It often grows on very thin soil on top of limestone rocks, often in association with white cedars. I identify this sedge by its fine-textured appearance and habitat because it flowers briefly and often sparsely. It is not anymore difficult to propagate from seed than other sedges – I have grown it from seed, and Otter Valley Native Plants used to offer it from time to time; its absence from native plant catalogues might be due to the difficulty in acquiring seed in quantity.

As a garden plant, it can thrive if protected from competition of other, taller herbaceous plants. It fares better as an element in a shady rock garden than as a ground cover, although I could see it working beautifully in a restrained Japanese-style garden amid limestone rocks.

Carex eburnea growing on limestone pavement on top of Niagara Escarpment.

Pennsylvania sedge (Carex pensylvania – one ‘n’ is correct) is the likeliest sedge to make it as a star ground cover. It is naturally spreading in habit and will fill in faster than than the clumpers. It grows on dry hillsides under open oak forest and in coppices in prairies, so it has good drought-resistance in the garden. It is usually to be found on sandy soils, but it seems to be able to adapt to heavier soils in gardens. Penn sedge seeds sparsely, putting its energies into vegetative propagation, ie going sideways. This does not mean that it gallops around. In fact, in heavy shade or tight soil, it can be very slow to spread at all.

Pennsylvania sedge forming a natural "lawn" under oak trees.
Native sedges as evergreen ground cover.

There are some other evergreen sedges that are a little taller, and therefore a little more competitive against weeds, that can be used in masses in gardens. Common sedge (Carex blanda) and slender sedge come to mind. I’ll try to track down some photos to post anon.

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Trish Murphy

Artist: botanical, still life, and natural history illustration. Garden designer: native plants and naturalistic gardens