Seed spacing: 60–100 cm between rows, 15–30 cm between plants. The normal
plant population is about two or three plants per square metre.
Depth: 2–4 cm
GROWTH CONDITIONS
Day length: day-neutral.
Growth period: the average is 125–160 days. Some dwarf varieties can mature in
45 days.
Temperature: sunflowers are fairly resistant to both heat and cold, and are not
damaged by mildly freezing temperatures that would kill maize or soybean. For
germination the soil temperature need only be about 8–10°C, much cooler than that
needed for maize or sorghum.
Rainfall: sunflowers are fairly drought resistant, and some varieties need only 400
mm if this is well distributed through the growing season.
Altitude: lowlands and medium altitudes are preferable.
Rotation: to avoid root rots sunflowers should not be grown on the same land more
often than every four years, nor should they follow peas, beets or potatoes.
Pests: not normally a serious problem, though cutworms, wireworms, grasshoppers,
aphids, weevils and other insects do feed on sunflower plants. Often the worst
damage is caused by the Sunflower (Head) Moth, whose larvae attack the seed.
The plant is also damaged by the Sunflower Leaf Beetle which feeds on the leaves,
and the Sunflower Maggot which tunnels into the stem.
Sunflowers are also very susceptible to damage by birds and rodents.
Diseases: the three most important are:
- Rust—dark brown spots, which turn black, on the underside of leaves, which turn
yellow, dry up and fall off. Up to 50% yield loss can occur. Some varieties have
good resistance; crop rotations and dusting with sulphur also limit this disease. - Grey Mould—worst in warm, humid conditions. Infects both the leaves and the
ripening seed head. - Stem Rot (Wilt)—caused by Sclerotonia sclerotiorum.
Other diseases include Powdery and Downy Mildews, White Rust, Verticillium
Wilt, Charcoal Rot and Black Rot. Virus diseases are also sometimes seen.
YIELD
The global average sunflower yield in 2004 was 1.22 MT/ha, according to FAO. In
that year, the highest national average was recorded in Austria, at 2.69 MT/ha, and
the lowest average in Zimbabwe, at 308 kg/ha.
Giant sunflower varieties yield more seed per hectare than dwarf varieties, but
their seed normally contains a lower percentage of oil.
A typical yield of oil is around 225 kg/ha.