How to grow sunflower for making cooking oil

Sunflower is a fairly fast maturing crop with most varieties taking 85 to 100 days to maturity. The crop is popular for its oil which is clean and light with high level of linoleic acid (an essential fatty acid). Sunflowers can be grown as a full season single crop or an intercrop with maize, soybeans and/or sorghum.

Regardless of whether they are grown as a single crop or an intercrop, sunflowers should not be planted in the same field more than once every three to four years. Sunflowers, like soybeans, do not leave much residue, so on erosive fields consider planting a cover crop after sunflowers.

Planting site

Choose a sunny spot because sunflowers love direct sunlight. Sunflowers grow best on well drained soils, are tolerant of clay loam or silty clay loam soils and perform relatively well on sandy loam soils. They should not be grown on water-logged soils.

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Choose the right seeds

For high yields, do not plant traditional varieties. Choose hybrid which have been developed for superior characteristics such as uniformity and high yields. Hybrid seeds are also consistently reliable unlike the traditional seeds which often become top-heavy and fall over in wet or windy weather. Hybrids have been selected for a strong, thick stalk to support its heavy head.

In ideal growing, you will have a crop that produces huge seed heads. Several varieties of sunflower are available in the market. Almost all commercial varieties of sunflowers are hybrids which requires that new seed should be bought each growing season. 

Plant early

Planting early can allow sunflower to be harvested before corn and soybeans, and will likely avoid any bird damage. Planting late can allow planting after other crops are done, and is less likely to have damage from sunflower moth. Sunflowers should be planted 1 to 1-½ inches deep and about 6 inches apart after the soil has thoroughly warmed.

If you wish, you can plant multiple seeds and thin them to the strongest contenders when the plants are six inches tall.  Give plants plenty of room to bloom, especially for low-growing varieties that will branch out. Make rows about 30 inches apart. A light application of fertiliser at planting time will encourage strong root growth to protect them from blowing over in the wind.

Proper fertiliser application

Feed plants only sparingly; too much fertiliser can cause stems to break. Use DAP (60 kg per acre) or 3 tonnes per acre of well-rotted farmyard manure or compost, applied two to three weeks before sowing. Mix fertiliser properly with soil before planting to avoid damaging the seeds, which leads to poor emergence. Avoid applying the fertiliser directly to the stem. Consider liming if the pH is below 6.0, to improve nutrient availability in the soil.

Disease control

Relatively few diseases affect sunflower crops. In cool wet soils, seeds or seedlings may be attached by fungi, it is therefore advisable to treat seeds before planting.

Various leaf and foliar diseases will cause surface spots or yellow patches, but do not affect the yield. Notably, the greatest disease threat to sunflower are sclerotinia (white mold), downy mildew, rust, and powdery mildew. using appropriate fungicides and crop rotation can reduce the effects of the disease.

[The writer is an expert on sustainable agriculture and agricultural solutions]