Common Name: Giant Sunflower

General Information

Helianthus giganteus is a herbaceous perennial plant growing from a rhizomatous rootstock and forming a clump of erect stems around 100 - 400cm tall[].
The plant is harvested from the wild for local use as a food and medicine.
Helianthus giganteus is reported to be stable and secure across the majority of its native range. The plant is classified as 'Least Concern' in the IUCN Red List of Threatened Species(2016)[].

Known Hazards

None known

Botanical References

, ,

Range

Central and eastern N. America - Ontario to Newfoundland, south to Kansas, Mississippi and Georgia

Habitat

Damp or rich thickets, swampy woods and clearings[]. Ususally found in wet open sites; at elevations from 10 - 600 metres or more[].

Properties

Conservation Status	Least Concern
Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Perennial
Height	3.60 m
Growth Rate	Fast
Pollinators	Bees, Flies
Cultivation Status	Wild

Cultivation Details

Succeeds in most soils in a sunny position[]. Requires a rich soil[]. Dislikes shade[]. Likes moist soils, doing well by a stream[].
The young growth is extremely attractive to slugs, plants can be totally destroyed by them[].
Members of this genus are rarely if ever troubled by browsing deer or rabbits[].
Plants have a running root system and can be invasive[].

Edible Uses

Tubers - cooked[]. A similar taste to Jerusalem artichokes but less productive. The var. 'subtuberosus' is used[, ].
Seed - raw or cooked. It can be dried and ground into a powder, then mixed with cornmeal and used for making bread[, , , , ]. The seed is very small and fiddly to use[].

Medicinal

The plant was ground into powder and used medicinally by the Cherokee to induce sneezing[].

Other Uses

Helianthus giganteus is a tertiary wild relative of the cultivated Sunflower Helianthus annuus, and has already been used to confer fertility restoration genes, and cytoplasmic male sterility to the cultivated Sunflower. It also belongs to Taxon Group two of the Jerusalem Artichoke Helianthus tuberosus[].

Propagation

Seed - sow spring in a cold frame. When they are large enough to handle, prick the seedlings out into individual pots and grow them on in the greenhouse for their first winter. Plant them out into their permanent positions in late spring or early summer, after the last expected frosts.
Division in spring or autumn. Very easy, larger clumps can be replanted direct into their permanent positions, though it is best to pot up smaller clumps and grow them on in a cold frame until they are rooting well. Plant them out in the spring.
Basal cuttings in spring. Harvest the shoots when they are about 10 - 15cm long with plenty of underground stem. Pot them up into individual pots and keep them in light shade in a cold frame or greenhouse until they are rooting well. Plant them out in the summer.