Tall Flatsedge
Cyperus eragrostis
Last reviewed: August 2026
Cyperus eragrostis (Tall Flatsedge) is a native grass-like sedge found across 11 US states from California to New Jersey. This moisture-loving plant blooms from May through September in full sun conditions.
Toxicity unknown
Tall Flatsedge (Cyperus eragrostis) is not listed by the ASPCA Animal Poison Control Center (opens in new tab) or the other sources we check, so we have no verdict for it either way. Absence from those lists is not a clearance. If your pet shows symptoms after eating any plant, call the ASPCA at (888) 426-4435.
Light
full sun
Water
high
Size
12"–36" H × 6"–18" W
Bloom
May, Jun, Jul, Aug, Sep
Native to
AL, CA, FL, LA and 7 more states
Before you buy
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Cities and water utilities offer rebates for replacing lawn with native and water-wise plants. We track 437 programs across 44 states, each with a link to the provider and the date we last checked it.
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Tall flatsedge is a native sedge that forms clumps of narrow, grass-like foliage reaching up to 3 feet tall. It produces small brown flower clusters from late spring through fall and thrives in consistently moist to wet conditions. This plant works well in rain gardens, pond edges, and other areas with regular water availability.
Growing Tall Flatsedge
Grow Tall Flatsedge in full sun and high water. Mature plants reach 12 to 36 inches tall and spread 6 to 18 inches wide. Expect low maintenance to keep it looking intentional in a front yard.
In an HOA neighborhood
Tall Flatsedge takes more care to keep looking intentional in a front yard. Maintenance level: low. Consider it for backyard or mid-zone beds rather than the street edge.
Works well in: backyard only.
- Appears wild and unmaintained to untrained eyes
- Brown seed heads can look messy
- May be mistaken for weedy grass or volunteer vegetation
Wildlife value
The seed heads provide food for birds, particularly waterfowl and songbirds. The dense clumps offer nesting sites and cover for small wildlife.
Common questions
- Where does Cyperus eragrostis naturally grow?
- Tall Flatsedge is native to 11 US states including Alabama, California, Florida, Louisiana, Mississippi, New Jersey, Oregon, Pennsylvania, South Carolina, Texas, and Washington.
- When does Tall Flatsedge bloom?
- Cyperus eragrostis produces flowers from May through September, providing an extended blooming period throughout the growing season.
- What growing conditions does Tall Flatsedge prefer?
- This sedge thrives in full sun locations with consistently high moisture levels, making it ideal for wet areas and water gardens.
- Is Tall Flatsedge HOA-friendly?
- Tall Flatsedge takes more care to look intentional in a front yard. Consider it for backyard or mid-zone beds rather than the street edge.
These answers were drafted with an AI model from this plant's data. Verify care details with a local expert.
Native range data from vouchered herbarium specimen records and regional native plant society lists. Pollinator and host plant associations compiled from GBIF, iNaturalist, and published ecological literature.
Ready to grow Tall Flatsedge? Add it to your garden in Pollinator Patch to track it and get season-by-season care guidance.
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