Giant Sunflower
Helianthus giganteus
- Plant Type
- Forb/herb (Deciduous)
- Landscape Layer
- Herbaceous
- Sun
- ☀️ Full Sun, ⛅ Part Sun
- Moisture
- 💧 Regular, 💧💧 High
- Soil
- Clay, Loam, Sand, Silt, Organic / Peat, Calcareous
- Bloom
- July, August, September
- Sociability
- S3 – Small colonies
Pollinator Value
- 🔑 Keystone
- Helianthus is a top-tier keystone genus in Ecoregion 8, supporting 52 species of butterflies and moths as larval host plants. The genus ranks among the most important Asteraceae for lepidopteran biodiversity in eastern North America, providing critical caterpillar food resources for species including Great Leopard Moth, Isabella Tiger Moth, and Milbert's Tortoiseshell.
S13 52 lepidoptera species for genus Helianthus
- 🐛 Larval Host
- Hypercompe scribonia, Pyrrharctia isabella, Orgyia leucostigma, Euxoa albipennis, Ogdoconta cinereola, Euxoa ochrogaster, Aglais milberti
- 🐝 Specialist Bee Host
- Andrena aliciae, Andrena chromotricha, Andrena helianthi, Colletes americanus, Megachile inimica, Megachile pugnata, Melissodes agilis, Melissodes denticulatus, Melissodes illatus, Melissodes trinodis
S17 genus-level Helianthus specialists with Eastern NA ranges; S3 OWSL specialist bees listed
- ❄️ Winter Food Source
- Sunflower achenes persist on standing dead stems through winter, providing critical seed food for Mourning Dove, American Goldfinch, Black-capped Chickadee, White-breasted Nuthatch, Tufted Titmouse, Northern Bobwhite, and White-winged Crossbill. Standing stalks also offer cover for small mammals and overwintering invertebrates.
S57 39 bird species at genus level; S10 specific bird species listed
Ecology & Conservation
- Proximity Score
- 2
- Native Status
- ❌ Outaouais ❌ Ottawa ❌ QC ✅ ON
- Closest Direction
- SE
- CEC Eco-Regions
- 8 – Eastern Temperate Forests, 8.1 – Mixed Wood Plains, 8.1.7 – Northeastern Coastal Zone
- Rarity Notes
- Secure (S5) in Ontario with abundant populations across the province. Not ranked in Quebec where it is considered introduced. Not listed under SARA or COSEWIC. Globally ranked G5 (Secure) by NatureServe. Rare and state-listed as endangered in Illinois at the southern edge of its range.
S22 G5, S5 ON, SNA QC; S26 not SARA listed; S10 rare in Illinois
- Rarity Ranks
- QC SNA – Not Applicable, ON S5 – Secure
- Migration
- Stable
- Ecological Context
- Giant sunflower occupies moist to wet open habitats including wet prairies, calcareous fens, sedge meadows, swamp margins, and floodplain edges. It is native to Ontario but introduced in Quebec. In its core range it associates with Solidago, Eupatorium, Verbena hastata, and Liatris spicata in wet prairie communities. It tolerates both limestone and juglone conditions.
S10 wet sand prairies, calcareous fens, sedge meadows; S7 wet prairies, fens, river banks; S3 tolerates limestone and juglone; S1 introduced in QC
Permaculture & Companion Planting
- Roles
- Fortress/Barrier, Pollinator Attractor
S73/S29/S72 Evidence: Fortress/Barrier: S61 keyword match: spines? (supporting signal only)] | Pollinator Attractor: S73 [HIGH]: S64 Xerces listed (source-classified)]
- Notes
- Pairs well with other tall wet-prairie species in moist meadow plantings. Complementary species from OWSL include Pale-spike Lobelia, Stiff Goldenrod, Yellow False-sorghum, New England Aster, and Canada Germander. Its rhizomatous habit and height make it suitable for background plantings in rain gardens and bioswales alongside shorter moisture-loving forbs. Tolerates juglone, so compatible with black walnut.
S3 complementary plants; S29 sunny edge; S3 tolerates juglone
Medicinal Properties ℹ
Always consult a qualified healthcare provider before using any plant for medicinal purposes. The information provided is compiled from secondary sources for educational purposes only.
Click here for more info →
ℹ
Always consult a qualified healthcare provider before using any plant for medicinal purposes. The information provided is compiled from secondary sources for educational purposes only.
Click here for more info →- Category
- Errhine
S28 Drug, Nose Medicine – used to induce sneezing
- Notes
- Cherokee traditional medicine: dry powder from the plant sprinkled to induce sneezing, used as a nasal remedy (errhine). PFAF medicinal rating is 0/5, indicating no widely recognized medicinal applications beyond this single ethnobotanical record.
Edibility & Foraging ℹ
Never ingest a plant unless you have 100% certainty of its identity and have consulted multiple reputable sources. The information provided in the Localeaf Plant Database is compiled from secondary sources for educational and historical purposes only.
Click here for more info →
ℹ
Never ingest a plant unless you have 100% certainty of its identity and have consulted multiple reputable sources. The information provided in the Localeaf Plant Database is compiled from secondary sources for educational and historical purposes only.
Click here for more info →❌ Not Edible
- Foraging Notes
- PFAF rates edibility 3/5. The tubers of var. subtuberosus can be cooked and taste similar to Jerusalem artichoke but are less productive. Seeds can be eaten raw or cooked, dried and ground into powder mixed with cornmeal for bread, but are very small and fiddly to use.
S29 tubers cooked, seed raw or cooked, very small
- Toxicity
-
☠️ High Toxicity
Not listed in Cornell poisonous plants database. PFAF reports no known hazards. However, LBJ Wildflower Center notes that stems and leaves can cause skin irritation in humans and that the plant can be fatal to animals if ingested. Exercise caution with livestock exposure.
S38 not listed; S29 no known hazards; S4 skin irritation warning
Seed Source
- Prairie Moon