Giant Sunflower
Helianthus giganteus
- Native to:
- Canada, United States
Oceancetaceen - Alice Chodura
Taxonomy
- Division:
- Magnoliophyta | - Flowering plants
- Family:
- Asteraceae
- Genus:
- Helianthus
- Species:
- Helianthus giganteus
- USDA Symbol:
- HEGI
Growth Characteristics
- Life Cycle:
- Perennial
- Growth Habit:
- Forb/herb
- Height:
- 300 cm
- Light Requirements:
- Full Sun
- Drought Tolerance:
- Low
- Bloom Months:
- aug,sep,oct
- Bloom Colors:
- yellow
Wildlife Benefits
- Bees:
- ★☆☆☆☆ Documented bee visitation (GBIF)
- Butterflies & Moths:
- ★☆☆☆☆ Documented Lepidoptera association (GBIF)
- Caterpillars:
- ★☆☆☆☆ Recorded caterpillar host plant (HOSTS Database)
Keystone Species Ranking
- Caterpillar Keystone:
- ★★★★☆ Butterfly & moth species supported by this genus (NWF)
- Pollen Specialist Bee Keystone:
- ★★★★★ Native pollen specialist bee species supported by this genus (NWF)
Host Plant for Caterpillars
Cremastobombycia ignota, Eucosma sombreana, Gnorimoschema ambrosiaeella, ⚠️maritime borer moth (Papaipema maritima), ⚠️Papaipema necopina (Papaipema necopina)
Reported Fauna Sightings
Bees: American bumble (Bombus pensylvanicus), Brown-belted bumble bee (Bombus griseocollis), Confusing bumble bee (Bombus perplexus), Half-black bumble bee (Bombus vagans), Red-belted bumble (Bombus rufocinctus), Sanderson bumble bee (Bombus sandersoni), Tri-colored bumble bee (Bombus ternarius) Butterflies:Gray Hairstreak (Strymon melinus)
Garden & Ecology Notes
- Wildlife Value:
- bees, butterflies, birds, small mammals
- Fire Ecology:
- Fire adapted — tolerates or benefits from fire
- Fire Notes:
- Resprouts vigorously from rhizomes following fire; historically maintained by prairie fires.
Soil Requirements
- Soil Type:
- moist, rich, well-drained loamy soil
- pH:
- 5.5 - 7.0 (slightly acidic to neutral)
- Drainage:
- tolerates poor drainage
- Moisture:
- consistently moist
- Notes:
- prefers wet meadows and marshy areas
Propagation & Germination
- Stratification:
- Cold/moist stratification required — 30–60 days
- Germination Time:
- 14–30 days
- Notes:
- Seeds germinate readily after cold stratification; light may improve germination rates.
The above propagation data sourced from Claude AI
Pre-treatment: Single-step cold-moist stratification for temperate woodland species. for 60–120 days
Source: Claude AI
ORGHPS Germination Guide: Sow @ 4C for 3 weeks, then place @ 20C.