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Swamp Sunflower

Helianthus angustifolius, also known as narrow-leaf sunflower or swamp sunflower, is a native perennial in the aster family.

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Updated:

August 7, 2025

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Swamp sunflower (Helianthus angustifolius)

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Swamp sunflower is a large, erect plant that can grow up to 8 feet tall with blooms of yellow daisy-like flowers in late summer into fall. The dark green leaves are narrow, willowy, hairy, and pointed at the tip with three linear veins. The tall stems are green to purplish. Swamp sunflower can be found up and down the East Coast, from New York to Florida. H. angustifolius has a medium growth rate and is a low-maintenance herbaceous perennial. This species is listed as threatened in Pennsylvania, Illinois, and New York.

Growing Conditions

H. angustifolius prefers moist to occasionally wet acidic sandy to clay loams in full sun. The plant can tolerate part sun but will see reduced flowering. To encourage branching, prune the plant back in June. The tall, flimsy stems may require staking, especially in windy locations. Hardy from USDA zones 5a to 9b.

Ecological Value: Wildlife, Insects, Etc.

The flowers of H. angustifolius provide nectar to pollinators from late summer until the first frost. It is also a host plant for the Silvery Checkerspot, Gorgone Checkerspot, Bordered Patch, and Painted Lady butterfly caterpillars. The seeds, when left to stand on dead flower heads, provide winter food sources for birds such as ruffed grouse, songbirds, quail, mourning doves, and even small mammals. Members of the genus Helianthus also support a variety of specialized bees, including long-horned bees, sweat bees, and leafcutter bees.

Landscaping

Commonly used in the back border of pollinator gardens, naturalized areas, rain gardens, restoration projects, and along streams or ponds. If you give it room, it will grow and spread, providing an abundance of color in your late-season garden beds.

Ethnobotany

Commonly used among Native Americans, seeds were ground or pounded to make flour for bread and cakes. Dyes from the plant were used for textiles, body painting, and decorations.

Pests and Diseases

Although it is common for caterpillars and beetles to chew on their leaves, damage is usually minimal and does not require management. Rust, leaf fungal spots, and powdery mildew are somewhat common.