GARDENING

WHEN are grasses not grasses? When they’re rushes or sedges. The latter are an attractive alternative to grasses and thrive where grasses couldn’t: woody, shady, wet and soggy spots, even pond margins.

Confusingly, some nurseries and garden centres label sedges as grasses. So, if you fancy the thought of sedges, you need a clear idea of how they differ from grasses.

A fine old ditty describing the crosssection of stems should help: “Rushes are round and sedges have edges, but grasses, like a***s, have holes.” Rushes have solid stems usually filled with pith, sedge stems are triangular in section, but grass stems are hollow pipes.

The stems of sedges are always solid, with three leaves coming up from the lower part of the stems, giving them a triangular appearance. They can be more striking than many grasses, and the larger species, such as Carex pseudocyperus, make a stunning addition to a display, having a mass of fine flowers drooping from 1m-tall green stems that turn golden brown in autumn.

Another clue for horticultural sleuths is the Latin name. Most sedges are in the genus Carex, the largest member of the Cyperaceae family. Other genera are Trichophorum, which includes deergrass; Eleocharis with the spike rushes; and Eriophorum including the cottongrasses. The common names don’t help: common cottongrass with its fluffy, white cottonwool seed heads is no grass but rather Eriophorum angustifolium.

There’s a good choice of sedges for shady bogs and ponds. Carex pseudocyperus is a fine specimen plant, its golden-brown flowers drooping elegantly from yellowygreen stems. And C paniculata, tussock sedge, forms dense clumps beside a pond. Its mass of feathery flowers turns black when the seeds ripen.

Although most of the readily available sedges are pond marginals, some will also cope with damp, wet areas that aren’t quite bogs or ponds. In part of my garden, we’ve let some fine hardwoods, including an elm, grow away and cast their shade. But we’re also cursed by living next to one of the sitka spruce plantations that darken and smother so many hills in the Borders.

I’ll park my dislike of variegated plant leaves and consider some low-growing C siderostichas. Shima-nishiki’s golden variegation is better than the white paint splashes of variegata.

As a genus with more than 1,500 species, it’s no surprise that some sedges need dry, sunny places as well. As an evergreen, C divulsa is invaluable, forming a mound of striking dark-green leaves. At 35-45cm, it will sit at the edge of a dryish border.

C aurea, golden sedge, is another possibility. This tough dwarf plant has bunches of round green seeds, gradually infused with orange, springing up from a mound of golden foliage.

Although some more unusual sedges are available as plants, you may need to grow other varieties from seed. C gravi, mace sedge, grows to 45-60cm, sprouting distinctive star-like seed heads. It’s ideal if you like cut flowers.

Coastal gardeners should consider C flacca, glaucus sedge, with brown-purple flowers in late summer. Provided it’s in a sunny place with alkaline soil, it’ll handle damp or dry ground.

But, when choosing sedges, think twice when you see them described as “vigorous” and “spreader”. C riparia, greater pond sedge, is a headache in waiting. And Arundo donax is probably worse.

PHOTOGRAPH: SHUTTERSTOCK Sedges are ideal for planting next to ponds or in boggy areas