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Common Name: Sunflower

General Information

Helianthus annuus is an annual plant that can grow up to 3.00 metres tall.
It has medicinal uses.

Known Hazards

None known

Botanical References

, ,

Range

Widely distributed throughout N. America. An occasional garden escape in Britain.

Habitat

Open dry or moderately moist soils on the plains[].

Properties

Edibility Rating
Medicinal Rating
Habit	Annual
Height	3.00 m
Growth Rate	Fast
Pollinators	Bees, Flies
Self-fertile	No
Cultivation Status	Wild

Cultivation Details

An easily grown plant, it succeeds in most soils[, , ], including poor soils provided they are deep and well-drained[], but it grows best in a deep rich soil[, ]. Plants are intolerant of acid or waterlogged conditions[]. Especially when grown for its edible seed, the plant prefers a sunny position[, , , ] though it also tolerates light shade[]. Requires a neutral or preferably calcareous soil[]. As sunflowers have highly efficient root systems, they can be grown in areas which are too dry for many other crops[]. Established plants are quite drought-resistant except during flowering[, ]. The sunflower tolerates an annual precipitation of 20 - 400cm, an average annual temperature in the range of 6 - 28°C and a pH in the range of 4.5 - 8.7[].
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[].
The sunflower is a very ornamental plant that is widely grown in gardens and is also a major commercial crop for its edible seed and many other uses[, ]. It grows well in Britain, but it does not ripen its seed reliably in this country and so is not suitable for commercial cultivation at the present[]. It is the state flower of Kansas[].
Three distinct groups of sunflowers are cultivated:-
Giant types grow from 1.8 - 4.2 metres tall with flower heads 30 - 50cm in diameter. The seeds are large, white or gray in colour, sometimes with black stripes, and are the best for culinary purposes, though the oil content is lower than for other types. 'Grey Stripe', 'Hopi Black Dye', 'Mammoth Russian' and 'Sundak' are examples of this type[, , ].
Semi-dwarf types grow from 1.3 - 1.8 m tall, are early maturing and have heads 17 - 23 cm diameter. The seeds are smaller, black, gray or striped, the oil content is also higher. Examples include 'Pole Star' and 'Jupiter'
Dwarf types grow from 0.6 - 1.4 m tall, are early maturing and have heads 14 - 16 cm in diameter[269. The seeds are small but the oil content is the highest. Examples include 'Advance' and 'Sunset'[].
Some forms are being bred for greater cold tolerance and should be more reliable in Britain[, ]. Plants tend to grow better in the south and south-west of England[]. Most forms require a four month frost-free growing season[], though some Russian cultivars can mature a crop in 70 days[]. When plants are grown in cooler latitudes the seed contains higher proportions of polyunsaturated fatty oils[].
The plant has a strong taproot that can penetrate the soil to depth of 3 metres, it also has a large lateral spread of surface roots[].
Sunflowers grow badly with potatoes but they do well with cucumbers and corn[, , ]. A very greedy and vigorous plant, it can inhibit the growth of nearby plants[]. Plants tend to impoverish the soil if they are grown too often in the same place[].
A good bee plant, providing large quantities of nectar[, , ]. The flowers attract beneficial insects such as lacewings and parasitic wasps[]. These prey on various insect pests, especially aphis[].

Edible Uses

None known

Medicinal

A tea made from the leaves is astringent, diuretic and expectorant, it is used in the treatment of high fevers[]. The crushed leaves are used as a poultice on sores, swellings, snakebites and spider bites[, ]. The leaves are harvested as the plant comes into flower and are dried for later use[].
A tea made from the flowers is used in the treatment of malaria and lung ailments[, ].
The flowering head and seeds are febrifuge, nutritive and stomachic[]. The seed is also considered to be diuretic and expectorant[, , ]. It has been used with success in the treatment of many pulmonary complaints[].
A decoction of the roots has been used as a warm wash on rheumatic aches and pains[].

Other Uses

None known

Propagation

Seed - sow in mid spring in situ. An earlier start can be made by sowing 2 - 3 seeds per pot in a greenhouse in early spring. Use a fairly rich compost. Thin to the strongest seedling, give them an occasional liquid feed to make sure they do not become nutrient deficient and plant them out in late spring or early summer.
Seed, harvested at 12% moisture content and stored, will retain its viability for several years[].