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Cyperus odoratus

fragrant flatsedge

Cyperaceae

North America and warm regions worldwide

Deer Resistant Container Friendly

Native to North America

SunFull Sun – Part Shade

WaterHigh

HardinessZones 5–9

Overview

Cyperus odoratus is a clumping annual or short-lived perennial sedge found across much of North America and warmer regions worldwide, with triangular stems 8-36 inches (20-90 cm) tall rising from fibrous roots. The grass-like leaves are flat, pale green, and mostly basal, while each stem is topped by a branched cluster of flower spikes subtended by several long leaf-like bracts that spread out below the head. The narrow spikelets are flattened and turn reddish-brown to golden as the seed matures, breaking apart into one-seeded segments at maturity, a trait that sets it apart within the flatsedges. C. odoratus grows in wet ground along pond and stream margins, ditches, marshes, mudflats, and seasonally flooded depressions, often colonizing bare wet soil quickly from seed. It tolerates a range of soils as long as moisture is steady but is not drought-tolerant. As an annual in much of its range, it completes its cycle in one season, which means a planting must reseed to persist. Its weedy spread on wet ground can crowd smaller plants in cultivation.

Native Range

Cyperus odoratus is native across temperate and tropical North America and occurs widely in warm regions worldwide. It grows on wet margins of ponds, streams, ditches, marshes, and mudflats, and in seasonally flooded low ground.

Suggested Uses

C. odoratus is used in rain gardens, pond and ditch margins, and wetland restoration seeding where quick cover of bare wet soil is wanted. Its seed feeds waterfowl and wetland birds. Its weedy reseeding makes it suited to naturalistic wet plantings rather than tidy borders.

How to Identify

Identify C. odoratus by its triangular stems topped with a branched head of flattened spikelets and several long spreading leaf-like bracts beneath. The spikelets turn reddish-brown to golden and break apart into small one-seeded segments as they ripen, rather than shedding loose seed. The pale green leaves are mostly clustered at the base. Its wet-ground habit and disjointing spikelets separate it from other flatsedges.

Appearance

Size & Dimensions

Height8" - 3'

Width/Spread8" - 1'6"

Colors

Flower Colors

Foliage Colors

Fall Foliage Colors

Bloom Information

Bloom Period

~12 weeks

Summer Fall

C. odoratus produces wind-pollinated flower spikes from summer into autumn, roughly July through October, with the timing tied to water and warmth. The spikelets shift from green to reddish-brown as seed matures over several weeks. Seed sheds through autumn and the plant dies back with frost in colder regions.

Detailed Descriptions

Flower Description

Reddish-brown to golden

Foliage Description

Pale green

Growing Conditions

Sun Requirements

SunFull Sun SunPartial Shade

Requires 4-10 hours of direct sunlight daily

• Full Sun: 6+ hours of direct sunlight

• Partial Shade: 3-6 hours of direct sunlight

• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range5.5 - 7.5(Neutral)

357912

Soil Types

loam clay sand silt

Drainagewet

Water & Climate

Water Needs

High

Frost Tolerance

tender

Time to Maturity

1-2 years

Care & Maintenance

Care Guide

C. odoratus grows in full sun to partial shade in consistently moist to wet soil with a pH of 5.5-7.5, tolerating sand, loam, clay, and mucky ground. It suits pond edges, rain gardens, and seasonally flooded spots and does not tolerate prolonged drought. Steady moisture during the growing season supports the heaviest growth and seed set. As a mostly annual sedge it relies on reseeding, so leaving some seed heads keeps a stand going. No fertilizer is needed on moist fertile ground. Pests and diseases are minor in open wet sites.

Pruning

C. odoratus needs no pruning. Spent stems can be cut after seed ripens, though leaving some heads allows the reseeding it depends on. In colder regions frost kills the top growth, which can be cleared in late winter.