Permapotes

Sunflower

Sunflower: Sowing, planting and harvest calendar

The annual sunflower (Helianthus annuus) belongs to the Asteraceae family and is native to North America. It is familiar for its large flower heads, edible seeds and the oil extracted from them. This description concerns the annual species. The genus Helianthus also includes perennial species with different life cycles and growth habits. The name sunflower therefore does not refer to just one form of plant.

Sunflowers develop sturdy stems and broad leaves, often rough in texture and toothed at the edges. Some varieties mainly produce one large terminal head, while others branch and carry several heads in succession. There are dwarf selections, intermediate forms and giants that can exceed several metres in favourable conditions. Height depends on the variety and the development of the plant, rather than automatically reaching four metres.

A flower head looks like a single large flower but contains many small flowers. The outer ray flowers carry the long structures usually called petals, while the central disc flowers are tubular. The contrast between the outer ring and the centre contributes greatly to its appeal. Colours are not limited to yellow: ornamental varieties can display cream, orange, red or brown shades, sometimes combined within the same head.

Russian Giant and Soraya illustrate two cultivar names encountered in gardens. Russian Giant belongs to the taller forms, while Soraya is valued as an ornamental sunflower and a cut flower. A variety may be chosen for height, branching, colour or seeds. These aims are not interchangeable. An imprecise name such as Spanish sunflower does not establish all the characteristics of a particular cultivar.

The structures commonly called seeds are dry fruits containing a single seed protected by a hull. Edible kernels are enjoyed plain or roasted and appear in bread, salads and various other dishes. Sunflower oil is another important use of the species. The outer ray flowers and young flower buds also have culinary uses, adding to the familiar uses of the seeds and their oil.

In a garden, sunflowers offer conspicuous blooms and interest for visiting insects and birds that eat the seeds. The annual completes its cycle after flowering and fruiting, but a branching plant can carry heads at different stages. This diversity explains the varying shapes and flowering periods seen among garden sunflowers.

Sunflower
Sunflower
Characteristics
  • Lifecycle : Annual
  • Exposure : Full Sun
  • Frost Hardiness : Frost Sensitive
  • Cultivation Difficulty : Easy
  • Mature height : 200 cm
Sowing & Planting
  • Greenhouse Growing : Not Required
  • Sowing Depth : 3 cm
  • Plant Spacing : 40 cm
  • Row Spacing : 40 cm
Maintenance
  • Maintenance : Moderate
  • Water Requirements : High
Other characteristics
  • Soil Type : Humus-rich
  • Soil pH Preference : Neutral
  • Pollination : Insect-pollinated
  • Propagation : Sowing