Giant Sunflower
Helianthus giganteus

Family: Asteraceae or Compositae

What it is like

Note: Helianthus giganteus var. subtuberosus Britton is a synonym of Helianthus giganteus L.

Helianthus giganteus is a PERENNIAL growing to 3.6 m (11ft 10in) at a fast rate. See above for USDA hardiness. It is hardy to UK zone 4. It is in flower from September to October, and the seeds ripen from October to November. The species is hermaphrodite (has both male and female organs) and is pollinated by Bees, flies. Suitable for: light (sandy), medium (loamy) and heavy (clay) soils and prefers well-drained soil. Suitable pH: mildly acid, neutral and basic (mildly alkaline) soils. It cannot grow in the shade. It prefers moist soil.

Height (m): 3.6

Where it is found

Damp or rich thickets, swampy woods and clearings.

N. America - Maine and Ontario to Saskatchewan, Florida, Louisiana and Colorado.

Conservation Status:

Countries/locations it is found in

How it is used

Food

Rating: 3

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.

Root: includes bulbs, corms, tubers, rhizomes etc.

Seed: includes nuts, cereals, peas and beans.

Medicine

Rating: 0

Other

Rating: 0

Food Forest: Plants for Edible Forest Gardens and Food Forests.

How it is grown

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. For polyculture design as well as the above-ground architecture (form - tree, shrub etc. and size shown above) information on the habit and root pattern is also useful and given here if available. The plant growth habit is a runner spreading indefinitely by rhizomes or stolons. The root pattern is rhizomatous with underground stems sending roots and shoots along their length.

Propagating it: 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.

Best place to grow: Woodland Garden Sunny Edge; Cultivated Beds;

Habit: Perennial

Hardiness: 4-8

Growth: Fast

Soil: Light (sandy), medium, heavy (clay)

Shade: No shade

Moisture: Moist

Things to keep in mind

Its other names

Local names

Synonyms

H. altissimus. H. decapitalus sulphureus elatior. H. giganteus var. subtuberosus Britton is a synonym of H. giganteus L.