Swamp Sunflower plant profile
Helianthus angustifolius
A perennial flower for full sun.
Last updated .
When to plant
When to plant Swamp Sunflower
A tall, aggressive perennial that prefers moist to occasionally wet acidic soils in full sun and flowers better in sun than in part shade. Propagate by division, root cutting, or seed, prune it back in June to encourage branching, and give it room to spread. It blooms from late summer into fall.
The calendar shows this cited seasonal window as an approximate band. It does not convert the season into frost-adjusted dates.
Open Swamp Sunflower in my garden calendarShows the source-backed planting season, not frost-adjusted dates.
Growing conditions
- Sun
- Full sun
- Lifecycle
- Perennial
- Spacing
- 12 to 36 in apart
- Hardiness
- Zones 5a to 9bFind my hardiness zone
Next steps
Continue with Swamp Sunflower
Evidence trail
Evidence behind this profile
Original extension and institutional publications behind the planting, care, and safety facts on this page.
- Helianthus angustifolius (Narrow Leaf Sunflower, Swamp Sunflower)
NC State Extension Gardener Plant Toolbox. Supports general reference. Checked 2026-06-18.