How to Combine Sedges with Garden Perennials
Native sedges (Carex) make great companions for garden perennials in sun or shade. Here are some combinations to try.
Sedges have enjoyed unprecedented attention the last few years. Articles in The Washington Post (2017), Horticulture (2022) and Landscape Architecture (2023) introduced many gardeners to plants in the genus Carex, which are commonly referred to as sedges.
While some colorful, variegated selections from Asia have been in cultivation for decades, recently the North American native sedges are getting attention. A 2023 trials report by Mt. Cuba Center put them squarely in the spotlight. The research team evaluated 70 different species and cultivars of native Carex for the Mid-Atlantic region.
That may seem like a big number, but it’s only a fraction of the more than 500 sedges native to North America. Given the range of species, there’s a sedge for every landscape situation. However, the availability of native sedges may be limited depending on where you’re located. The horticultural industry is aware of this and is eagerly bringing more of them into cultivation.
The attention is notable given native sedges’ low-key appearance. Their flowers tend to be small, and only a few species have showy blooms. Rather, their strength lies in their grasslike foliage and unfussy nature. They are perfectly suited to a supporting role in the garden.
Sedges’ varying shades of green provide a backdrop for flashier flowering companions. The narrow blades lend visual texture that contrasts beautifully with broader-leaved perennials. They’re relatively easy to grow and don’t require a lot of attention. They’re also go-to plants for partial sun to shade, where turf and warm-season ornamental grasses struggle.
Native sedges thrive in challenging sites
Carex is a versatile genus, offering species adapted to a range of natural and constructed environments.
Kathryn Ancaya of Living Roofs, Inc. is a landscape architect based in North Carolina. Her sedge combinations survive the tough conditions on green roofs, which are designed to capture water and drain quickly. Plants there must withstand periodic inundation by rainstorms and long periods of dryness in between. They need to stand up to the daytime heat in Southeastern summers and to the high nighttime temperatures that can zap plants’ reserves.
On the ground, one of Ancaya’s favorite combos—Texas sedge (C. texensis; Zones 5–9), nodding onion (Allium cernuum; Zones 4–8) and hairy beardtongue (Penstemon hirsutus; Zones 4–7)—translates well to hot, dry spots like the edges of pathways and the upper edges of rain gardens.
A large proportion of Carex species occur naturally in moist or wet environments. Bentley Ruggles, a landscape architect also based in North Carolina, uses eastern narrowleaf sedge (C. amphibola; Zones 3–9) on wet sites in combination with the upright architectures of soft rush (Juncus effusus; Zones 4–9) and blue flag iris (Iris versicolor; Zones 3–9).
Ruggles looks for plants that will thrive in saturated, low-oxygen soils. These and other moisture-loving species are useful at the edge of a pond or stream, in a drainage ditch or near the base of a downspout. When there are large areas to cover or plant bullies to counter, some of the larger, colonizing species like fox sedge (C. vulpinoidea; Zones 3–8) can give gardeners an edge.
Use short sedges as ground cover and for wildlife
Most of the sedges readily available to home gardeners are short—usually three feet or lower in height. These can be combined with low-growing perennials to provide benefits beyond what mulch or turfgrass can. They help suppress weeds, slow and clean stormwater, increase water infiltration and support wildlife. Many species of sedges host caterpillars and provide food, cover and nesting sites for birds and small mammals.
When it comes to gardening for wildlife, sedges help create “soft landings” for pollinators and beneficial insects. According to pollinator conservationist Heather Holm, many insect species spend part of their life cycle in trees and then drop to the ground to continue their development. Landing on a barren hardscape can be the end for them. Diverse native plantings under native trees provide critical habitat and shelter, giving them the environment they need to survive.
With sedges anchoring the ground layer, other perennials fill in and get a chance to show off their flowers. Green and gold (Chrysogonum virginianum; Zones 5–9), golden ragwort (Packera aurea; Zones 3–8), eastern columbine (Aquilegia canadensis; Zones 3–8) and dwarf crested iris (Iris cristata; Zones 3–9) are colonizers that have persistent basal foliage. They flower in spring, and that basal foliage holds ground across the entire year. I use these ground-covering perennials—along with wild blue phlox (Phlox divaricata; Zones 3–8) to ramp up the spring floral display—in combination with favorites Cherokee sedge (C. cherokeensis; Zones 6–9) and rosy sedge (C. rosea; Zones 3–8). The combinations adapt well to mixed sun and shade, a big deal when gardening under mature trees.
Use tall sedges in meadow plantings
In sunnier habitats, sedges tend to grow in climates where temperatures are cooler, where there’s consistent moisture or tucked beneath shrubby plants and taller perennials. Whether it’s sun or shade, carex are expert minglers. That’s why they’re well suited as the underplanting for taller perennials.
Arkansas bluestar (Amsonia hubrichtii; Zones 5–8) and false wild indigo (Baptisia australis; Zones 3–9) have a big presence in the garden. Eastern woodland sedge (C. blanda; Zones 4–8) and Eastern narrowleaf sedge (C. amphibola; Zones 3–9) are all excellent fillers for underneath these taller perennials, especially in mixed sun-shade areas. These sedges spread readily by seed, so make sure you put them where you want more.
Muskingum sedge (C. muskingumensis; Zones 4–8) is at home in consistently moist areas and has a gentle, spreading habit. Its palm-like foliage contrasts beautifully with the broad foliage and bright flowers of purple coneflower (Echinacea purpurea; Zones 3–8) and compact cultivars of Joe-Pye weed (Eutrochium), such as E. dubium ‘Little Joe’ (Zones 3–8).
Sedge foliage brings lasting interest
Sedge combinations are also an opportunity to focus on foliage. A mix of textures—fine foliage, bold foliage, different leaf shapes and sizes—provides visual contrast and allows you to create compositions with layers of interest beyond flowers and colors. Plantings that are primarily foliage driven retain their appeal throughout the growing season. They also give the viewer’s eye a place to rest; they’re soothing, and yet interesting enough to be engaging.
Ferns are classic foliage plants and excellent companions for sedges. The delicate fronds of lady fern (Athyrium filix-femina; Zones 3–8) play beautifully with the narrow blades of Appalachian sedge (C. appalachica; Zones 3–8), and both do well in rich, moist, well-drained soils.
For drier sites, try white-tinge sedge (C. albicans; Zones 3–8) and evergreen Christmas fern (Polystichum acrostichoides; Zones 3–9). Northern maidenhair (Adiantum pedatum; Zones 3–8) has intricate foliage and thin, black stems. It forms a lovely mélange of texture growing with the broad, bluish leaves of Bunny Blue sedge (C. laxiculmis ‘Hobb’; Zones 4–8) and the plump rosettes of woodland stonecrop (Sedum ternatum; Zones 4–8).
In a foliage-heavy combo, the broader bladed sedges contribute linearity with a visual boldness that feels lush. Like Bunny Blue, thinfruit sedge (C. flaccosperma; Zones 5–8) has wide, bluish leaves and it is tougher than it looks. Plaintainleaf sedge (C. plantaginea; Zones 3–8) is one of my favorites. Wide, dimpled leaves earn it the alternative common name of seersucker sedge. Mix these bold-textured sedges with the showy foliage of alumroot (Heuchera) or foamflower (Tiarella). Add white wood aster (Eurybia divaricate; Zones 3–8) for quick coverage and late season blooms.
5 sedge combinations to try
1. For full sun to part shade and wet soil:
Cherokee sedge (Carex cherokeensis), a 10- to 12-inch species with rich green foliage
Golden ragwort (Packera aurea), a semievergreen ground cover with dark, heart-shaped leaves and tall stalks of yellow flowers in spring
Wild strawberry (Fragaria virginiana), a cool-season ground cover with spring flowers and early-summer fruits
2. For sun or shade and dry soil:
Golden star sedge (Carex rosea), a compact species that grows as a tidy tuft of bright green leaves
Robin’s plantain (Erigeron pulchellus), an aster-like perennial with white flowers rising above a clump of paddle-shaped leaves in spring
3. For shade and wet soil:
Creek sedge (Carex amphibola), a foot-tall species with a decidedly fountainlike habit
Green and gold (Chrysogonum virginianum), a mat-forming perennial with daisy-like yellow flowers that repeat from spring to fall
4. For full sun to part shade and dry to moist soil:
Texas sedge (Carex texensis), a foot-tall species with foliage held in a tight bunch
Nodding onion (Allium cernuum), with 12-inch-tall clumps of strappy foliage and clusters of pink flowers in summer
Hairy beardtongue (Penstemon hirsutus), a compact penstemon with pink flowers in early summer and foliage that turns red in fall
5. For shade and dry to moist soil:
Creeping sedge (Carex laxiculmis), an evergreen species with straplike blue-green leaves
White wood aster (Eurybia divaricata), a sprawling perennial with heart-shaped leaves and abundant white flowers in late summer
Heart-leaf aster (Symphyotrichum cordifolium), an upright plant with blue flowers from late summer to fall
