swamp sunflower
Helianthus angustifolius · Asteraceae
swamp sunflower (Helianthus angustifolius) is a perennial herbaceous plant in the Asteraceae family. It is native to North America. USDA records it as hardy in zone 4 and warmer, down to about -28°F.
At a glance
| Type | forb-herb USDA |
|---|---|
| Lifecycle | perennial USDA |
| Native status | native USDA |
| Mature height | 5.6 ft USDA |
| Light | part-shade USDA |
| Water need | medium USDA |
| Growth rate | moderate USDA |
| Soil pH | 4–7 USDA |
| Bloom | August–September USDA |
| Flower color | Yellow USDA |
| Hardiness zones | 4 and warmer USDA |
| Guild layer | herb-layer Derived |
| Nursery availability | Routinely Available USDA |
USDA quoted from the USDA PLANTS database · Derived computed by a fixed rule from those columns. No value on this page is estimated.
Growing conditions
It grows in partial shade. USDA rates it as having moderate water needs. Its drought tolerance is rated medium. It will not tolerate waterlogged soil — USDA rates its anaerobic tolerance as none. It is recorded on soils from pH 4 to 7 — a broad range that spans acidic through mildly alkaline ground. Its cold limit is zone 4.
Size and growth
At maturity it reaches about 5.6 ft, making it roughly waist to chest height. It grows at a moderate rate.
Bloom period
USDA records a bloom period of August through September. Flowers are yellow.
A flowering date, not a pollinator rating.
Foliage, flower and season
Summer foliage is dark green, medium in texture. Its flowers are conspicuous. It carries conspicuous autumn colour. Its active growth period is spring and summer. USDA rates its lifespan as moderate.
What the site needs to provide
USDA records it across sites receiving 25 to 65 inches of annual precipitation. It needs at least 160 frost-free days to finish its season. It roots to at least 6 inches. Fertility requirement: low — no feeding needed on ordinary garden soil.
Propagating it
Propagate it from seed and sprigs. USDA records no cold-stratification requirement, so seed should germinate without a chilling period. Its seed spreads at a moderate rate. It spreads vegetatively at a moderate rate.
Resilience and wildlife
Browsing animals find it highly palatable, so expect deer and rabbits to take an interest. Its fire tolerance is rated medium. Its growth form is recorded as rhizomatous.
Role in a guild
Herb layer. In a layered planting this is the herbaceous middle — perennials and grasses that fill the space between ground cover and shrubs. The layer is derived by a fixed rule from growth habit and mature height.
Tags
Related plants
Others in Helianthus
- common sunflower Helianthus annuus
- cucumberleaf sunflower Helianthus debilis
- sawtooth sunflower Helianthus grosseserratus
- Maximilian sunflower Helianthus maximiliani
Similar role and hardiness
- Columbian monkshood Aconitum columbianum
- Colorado blue columbine Aquilegia coerulea
- mountain brome Bromus marginatus
- eastern woodland sedge Carex blanda
- scarlet Indian paintbrush Castilleja coccinea
Where this data comes from
Every value on this page comes from the USDA PLANTS database record for symbol HEAN2, or is computed from those values by a fixed rule. Nothing here is estimated or model-generated. Where USDA publishes no value, this page omits the claim rather than filling the gap.
- Quoted from USDA PLANTS: active growth period, Bloom, Bloom end, browse palatability, cold stratification, Drought tolerance, fall conspicuous, fertility requirement, fire tolerance, Flower color, flower conspicuous, foliage color, foliage porosity winter, foliage texture, frost free days min, fruit conspicuous, growth form, Growth rate, Hardiness zones, Lifecycle, lifespan, Light, Mature height, Minimum temperature, Native status, Nitrogen fixation, Nursery availability, precipitation max in, precipitation min in, propagation, resprout ability, root depth in, seed spread rate, Soil pH, Soil pH (upper), Tolerance of wet soil, Toxicity, Type, vegetative spread rate, Water need.
- Derived by a fixed rule from those columns: Guild layer.
Read our full data sources and methodology.
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