SEDGES ARE ALL AROUND US: holding stream banks in place; populating meadows, prairies and wetlands; carpeting woodlands; tufting rocky slopes; and feeding and sheltering wildlife. Their adaptability makes true sedges (Carex spp.) a natural fit in sustainable landscapes, and their varied textures are attractive as accents or background plantings. These grass-like perennials usually have solid triangular stems with sharp to rounded edges. Leaves range from short and fine-textured to big, bold and wide-bladed, and flowers and seed heads from modest to showy bristles or mace-like capsules.
Although it’s the largest genus of flowering plants in North America (about 500 species), plant biologist and Carex expert Dr. Robert Naczi says sedges are poorly understood in nature and few have been cultivated. “When people catch on to the diversity of colors, growth forms and growing conditions, they will embrace them in a big way,” he predicts. “There’s a sedge for every spot.”
Naczi, the Arthur J. Cronquist Curator of North American Botany at New York Botanical Garden, says, “Nearly every North American habitat hosts sedges. Although some sedges have large ranges, they tend to be very specific to habitat. There are relatively few generalists.” In nature, sedges may mingle or dominate specific niches that match their moisture, light or other needs. Life is easier in tended landscapes, where many species tolerate wider growing conditions.
Naczi applauds the recent introduction of tricky-to-propagate plantain sedge (C. plantaginea). It grows from Minnesota through eastern North America, in a narrow deciduous forest niche with rich, moist, relatively neutral-to-alkaline soils. But in the garden, this fairly broad-leafed beauty with shiny dark-green puckered leaves and black-tipped spring flowers thrives in light to deep shade, relatively acidic to alkaline S soils, and moist to somewhat dry conditions.
Michael Hagen, curator of NYBG’s Native Plant Garden, likes the way its tidy 1- to 2-foot clumps make room for trilliums and other woodlanders. Fine-textured 8- to 12-inch Pennsylvania sedge (C. pensylvanica) grows through underground stems (rhizomes), occurring sparsely in dry upland woods throughout the East alongside wild geraniums and shade-dwelling asters. It grows more densely on moist, sunny edges and can become a groundcover. Slightly coarser 1- to 2-foot semi-evergreen C. amphibola inhabits moist woods from Texas through the East into Canada. This clumping sedge colonizes beautifully by seed that ripens in spring. Diminutive tufts of heat- and drought-tolerant ivory sedge (C. eburnea) inhabit sandy limestone outcroppings and riparian zones from the Atlantic Coast to the Front Range of the Rocky Mountains, growing well under junipers and giving a “lawn look” to shady spots with low foot traffic.
Wildflower Center Director of Horticulture Andrea DeLong-Amaya praises the local heat-tolerant species some call Hill Country sedge (C. perdentata). “It’s bright green, really pretty and lush. I could see it as a lawn if you like the soft, mounded look. It’s a great substitute for monkey grass (or liriope), good lining a border where the brighter green really stands out and as a groundcover in shade.”
Senior Horticulturist Julie Marcus finds C. cherokeensis useful for rain gardens. Common in well-drained woodlands, it takes occasional inundation, while Texas sedge (C. texensis) prefers dry shade, such as well-drained caliche soils under junipers.
Taller sedges for wet places abound. Palm sedge (C. muskingumensis), a curvy, cold-hardy Midwesterner, is an exotic-looking replacement for invasive dwarf bamboo, suppresses weeds in normal to moist soils, works well in shrub borders and rain gardens, and in sun or light shade. Super-aggressive C. emoryi, a widespread wetlander, doesn’t play well with others, but its strong rhizomes bind alluvial soils to reduce flooding and rapidly colonize. Southeastern native C. oklahomensis takes standing water and makes a bold accent in Texas and Oklahoma water gardens. With such diversity, the list of useful sedges seems limited only by availability.
Luckily, experts like landscape designer Claudia West are devoted to promoting sedges. Co-author with Thomas Rainer of “Planting in a Post Wild World: Designing Plant Communities for Resilient Landscapes” (Timber Press) and the ecological sales manager at Pennsylvania’s North Creek Nurseries, she considers ecological, functional and aesthetic concerns together. “We need to move away from mulch and fill gaps in the landscape with plants to provide habitat and hold the soil. Sedges provide essential soil-building function and support wildlife. They may not be the showiest, but many are evergreen so you see them in winter – green, lush and gorgeous.”