The thin, often ornamentally colored or weeping leaves of sedge (Carex spp.) closely resemble those of ornamental grasses, though sedge is not grass. Sedge relish moist to wet soils in many different light exposures, making them popular for aquatic landscapes or soggy areas of the garden. Some ornamental sedges propagate so fast they become a weedy pest. But most grow well in average garden soils that are neither dry nor wet.
Sedge belongs to the papyrus family Cyperaceae; grass is in another family, Poaceae. There are over 1,500 different species of sedge worldwide, which range from being winter deciduous to evergreen, and from tufted to spreading via rhizome roots.
Sedges are primarily native to the Arctic and northern temperate zones of the world. A few species thrive in the tropics, but only in cooler montane regions that do not get tropical heat in summer. Sedges grow in bogs, moors, moist woodlands or on the edges of freshwater bodies.
Leaves of sedge generally possess a three-sided or ranked shape, which is noticeable when you try to spin a leaf or stem between your fingers. The leaf blades are linear and grass-like, but the stems lack the nodes that are present on grass stems. Loose clusters or pendent strings of grass-like flowers occur in spring or summer. The seeds dry and scatter from the mother plant and germinate nearby if soil is moist.
Sedges grow in three soil environments. The first group of sedges grow best in average garden soil which is never soggy or bone dry. The second group prospers in fertile soil that drains well but is consistently moist, and the last cultivation group needs moist to wet, saturated soil. All sedges enjoy full sun to partially shaded light exposures. Consult literature or plant labels on purchased plants for specific cultural needs based on the individual species. Some varieties may tolerate certain rare garden light or soil situations that the typical sedge does not.
Sedges grow quickly in rich soil with ample water and will drop huge numbers of seeds that germinate and create a weed situation. Many sedges seem immune to typical herbicides used in gardens for weed control. Although non-selective chemicals like glyphosate (Round-Up) can burn sedge foliage, the plant often bounces back with lush new growth. In sedges that become nuisance weeds, such as nut sedge, use a product with the active chemical ingredient halosulfuron (SedgeHammer or Manage) if hoeing fails as a means of control.