Helianthus giganteus
Giant sunflower
Hélianthe géant
Obsolete Names
- swamp sunflower
- tall sunflower
- soleil géant
No seeds available for this plant.
We are not accepting seeds for this plant at the moment.
Bloom colour: Yellow
Bloom period: July - September
Max Height: 8.0 feet
Max Width: 4.0 feet (spreads by rhizome)
Light condition:
More than 6 hours of direct sun a day
More than 2 or 3 hours but less than 6 hours of direct sun a day
Soil conditions:
Tolerates medium soil condition
More than 6 hours of direct sun a day
More than 2 or 3 hours but less than 6 hours of direct sun a day
Tolerates medium soil condition
Lifespan : Perennial
Gardener Experience:
Does not spread uncontrollably
Easy to germinate
Does not spread uncontrollably
Easy to germinate
Landscape uses:
Suitable for shoreline rehabilitation
Suitable for shoreline rehabilitation
Ecological Benefits:
Supports pollinators
Bee host
Supports pollinators
Bee host
Tolerates:
Tolerates limestone conditions
Tolerates juglone conditions
Tolerates limestone conditions
Tolerates juglone conditions
Plant Distribution
Native to Ottawa region: No
Thrives in Ecozones
- Atlantic Maritime
- Ecozone-Mixed Wood Plain
- Ecozone-prairies
- Ecozone-Montane Cordillera
- Ecozone-Boreal Shield
- Ecozone-Boreal_Plains
- Atlantic_Maritime
- Ecozone-Prairies
Butterflies Supported by Helianthus giganteus
- Phragmatobia fuliginosa (Ruby Tiger)
Bees Supported by Helianthus giganteus
- Andrena aliciae
- Andrena chromotricha
- Andrena helianthi
- Complexe Colletes americanus
- Dianthidium simile
- Megachile inimica
- Megachile pugnata
- Melissodes agilis
- Melissodes denticulatus
- Melissodes illatus
- Melissodes trinodis
- Perdita pallidipennis
Complementary Plants Plants that grow in similar conditions, that bloom at the same time.
- No complementary plants found.
Sowing Information
- Sowing depth: Sow just below surface
- Sow before March
- Stratification duration: 30 days
- Self-seeding
Harvesting Information
- Harvesting indicator: Seeds easily fall off when you gently pull them off
- Harvesting mean: Shake seed head in paper bag
- Seed Viability Test: No test needed before donating
- Packaging Measure: 1 rounded 1/4 teaspoon
- Seed Storage: Air Dry in paper bag or open container, for a few days until crisp, shaking seeds to move them once in a while to prevent molding
- On Cultivar: Yes, do not donate unless you know source, and there are no known cultivars in your garden or at proximity