How much sun does Atlantic Mannagrass need?

Atlantic Mannagrass grows best in part sun conditions.

When does Atlantic Mannagrass bloom?

Atlantic Mannagrass blooms in June, July, and August.

Where is Atlantic Mannagrass native?

Atlantic Mannagrass (Glyceria obtusa) is native to CT, DE, MA, MD and 9 more states, per vouchered herbarium specimen records and regional native plant society lists.

Is Atlantic Mannagrass toxic to livestock?

The USDA PLANTS Database does not flag Atlantic Mannagrass as toxic to livestock.

Is Atlantic Mannagrass HOA-friendly?

Atlantic Mannagrass takes more care to look intentional in a front yard. Consider it for backyard or mid-zone beds rather than the street edge.

Atlantic Mannagrass

Name: Pollinator Patch
Author: Pollinator Patch

Glyceria obtusa

Last reviewed: August 2026

Toxicity unknown

Atlantic Mannagrass (Glyceria obtusa) 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.

The USDA PLANTS Database (opens in new tab) does not flag Atlantic Mannagrass as toxic to livestock.

Light

part sun

Water

high

Size

12"–36" H × 6"–18" W

Bloom

Jun, Jul, Aug

Native to

CT, DE, MA, MD and 9 more states

Before you buy

Your city may pay you to plant this

Cities and water utilities offer rebates for replacing lawn with native and water-wise plants. We track 445 programs across 44 states, each with a link to the provider and the date we last checked it.

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Browse plants for this ecoregion

Northeastern Highlands Northeastern Coastal Zone Middle Atlantic Coastal Plain Northern Piedmont Southeastern Plains Acadian Plains and Hills Atlantic Coastal Pine Barrens

Atlantic mannagrass is a native wetland grass that forms clumps of narrow green leaves and produces delicate flower spikes in summer. This moisture-loving perennial thrives in consistently wet soils and partial sun conditions. It works well for rain gardens, pond edges, and other water-retention areas.

In an HOA neighborhood

Atlantic Mannagrass 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.

Requires consistently wet conditions that may appear problematic
Can look unkempt or weedy to conventional standards
Associated with wetland areas rather than traditional landscaping

Wildlife value

The seeds provide food for waterfowl and songbirds, while the dense growth offers nesting habitat for marsh birds. As a native grass, it supports various insects and contributes to wetland ecosystem health.

Common questions

How much sun does Atlantic Mannagrass need?: Atlantic Mannagrass grows best in part sun conditions.
When does Atlantic Mannagrass bloom?: Atlantic Mannagrass blooms in June, July, and August.
Where is Atlantic Mannagrass native?: Atlantic Mannagrass (Glyceria obtusa) is native to CT, DE, MA, MD and 9 more states, per vouchered herbarium specimen records and regional native plant society lists.
Is Atlantic Mannagrass toxic to livestock?: The USDA PLANTS Database does not flag Atlantic Mannagrass as toxic to livestock.
Is Atlantic Mannagrass HOA-friendly?: Atlantic Mannagrass takes more care to look intentional in a front yard. Consider it for backyard or mid-zone beds rather than the street edge.

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 Atlantic Mannagrass? Add it to your garden in Pollinator Patch to track it and get season-by-season care guidance.

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