Sunflower Growing Techniques Tutorial: A Detailed Guide to the Latest Cultivation Methods

The sunflower is native to South America. The domesticated variety was brought from North America to Europe by the Spanish in 1510, initially for ornamental use, and at the end of the 19th century it was introduced back to North America from Russia. It is cultivated throughout China and has very high cultivation value. The seeds are often roasted and eaten as a snack, and can also be pressed for sunflower seed oil; the oil residue can be used as feed. Now let us take a look together at the cultivation techniques for sunflowers!

Growing Conditions for Sunflowers

1. Temperature: The sunflower is a warmth-loving yet cold-tolerant crop, with strong adaptability to temperature. The seeds have very strong tolerance to low temperatures; when the soil temperature is stable above 2℃, the seeds begin to germinate, at 4-5℃ they can sprout and take root, and when the soil temperature reaches 8-10℃ it can meet the needs of seed germination and emergence. Throughout the entire growth process, the sunflower can grow normally as long as the temperature is not below 10℃.

2. Water: The sunflower is a crop that consumes a relatively large amount of water, with tall plants and many dense leaves; its water uptake is 1.74 times that of corn. However, because its growth and development mostly coincide with local rain and heat, the conflict between water supply and demand is not prominent, and the water requirements differ greatly at different growth stages. From sowing to budding, it needs little water; from budding to flowering is the peak water demand period; and from flowering to maturity the water demand is also relatively high.

3. Light: The sunflower is a short-day crop, but its response to day length is not very sensitive. It likes abundant sunshine, and its seedlings, leaves and flower heads all have strong phototropism. With sufficient sunshine, the seedlings are sturdy and can be prevented from growing leggy. With sufficient sunshine in the mid-growth period, vigorous stem and leaf growth can be promoted, flowering and pollination proceed normally, and the seed-setting rate is improved. With sufficient sunshine in the late growth period, the seeds are plump and full.

4. Soil: The sunflower has low soil requirements and can grow in all kinds of soil, from fertile soil to dry land, poor soil and saline-alkali land. It not only has strong saline-alkali tolerance, but also has salt-absorbing properties. At the same time, the sunflower has a well-developed root system and strong drought resistance. Moreover, the sunflower's roots and stems have well-developed aerenchyma, making it very tolerant of waterlogging.

The Growth Cycle of Sunflowers

1. Seedling stage: The period from emergence to budding in sunflowers is called the seedling stage; it generally takes 35-50 days, or 28-35 days for summer sowing. This period is the stage of leaf and flower primordium formation and floret differentiation. The seedling stage is when the sunflower has the strongest drought resistance; above-ground growth is slow, while the underground root system grows quickly and soon forms a strong root system.

2. Budding stage: From budding to flowering, the sunflower generally needs about 20 days. This is a period when vegetative growth and reproductive growth proceed together, and it is also the most vigorous stage of its life. During this period it needs the most fertilizer and water, about 40-50% of the total fertilizer and water requirement. If the need for water and fertilizer cannot be met in time, the yield will be seriously affected.

3. Flowering stage: For a single flower head of a sunflower, from the opening of the ray florets to the completion of the opening of the tubular florets generally takes 6-9 days. From the second day to the fifth day is the full bloom period, mostly opening at 4-6 a.m., with pollination on the following morning. Unpollinated stigmas can remain receptive for 7-10 days, but the seed-setting rate from self-pollination is only about 3%, while the seed-setting rate from cross-pollination is high.

4. Maturity stage: The maturity stage of the sunflower refers to the period from flowering to maturity, 25-55 days for spring sowing and 25-40 days for summer sowing, with differences among varieties. About 15 days after flowering and pollination is the seed formation stage. During the maturity stage, the sunflower needs clear weather, a relatively large difference between day and night temperatures, and suitable soil moisture.

Sunflower Cultivation Techniques

1. Site selection and land preparation: For sunflower cultivation, choose a plot with level land, medium fertility, convenient irrigation and drainage, and relatively low soil stickiness; continuous cropping is not advisable. It reproduces by seed, and peat soil is suitable for sowing. Before sowing, dress the seeds with new high-fat film, which can repel underground pests, isolate viral infection and increase the seed germination rate.

2. Timely sowing: The sowing time for sunflowers is generally March to April, and the suitable temperature for sowing is 18-25℃. Usually they sprout about 5-7 days after sowing. The basic principle for choosing the sowing date is to sow appropriately early or late according to the patterns of saline-alkali occurrence, so that the seedlings avoid saline-alkali damage. Spring or summer sowing is carried out according to the growth period of the variety.

3. Field inspection and replanting: The sunflower is a dicotyledonous crop, and it takes considerable effort for the seedlings to push through the soil. In addition, poor land preparation or sowing quality, or surface soil crusting after rain following sowing, or damage by disease, insects, rodents, birds and so on, can easily cause missing plants and broken rows. To ensure full stands after sowing, the fields must be inspected row by row during the emergence period, and replanting must be done promptly where plants are missing in patches or rows.

4. Thinning and final thinning: In sunflower cultivation, thinning should be done early to prevent seedlings from crowding each other, which affects the cultivation of strong seedlings and even later yield. As for saline-alkali land and plots with severe insect damage, the timing of final thinning can be appropriately delayed. At the same time, sunflowers should also be finally thinned early, which helps cultivate strong seedlings and also benefits flower head development; final thinning should be carried out at the 2-pair true leaf stage.

5. Cultivation and weeding: Sunflowers are generally cultivated 2-3 times, which serves to weed and loosen the soil, break up crusting, conserve water, reduce evaporation and alleviate saline-alkali damage. The first cultivation is carried out at the 1-2 pair true leaf stage together with thinning and final thinning; the second cultivation is carried out 1 week after final thinning; and the third cultivation is completed before row closure together with ditching, earthing up and fertilizing.

6. Ditching and topdressing: Sunflowers prefer fertilizer. Ditching and topdressing are usually carried out at the third cultivation, mainly with nitrogen and phosphorus fertilizer: 5 kg of diammonium phosphate and 10 kg of urea per mu, mixed evenly and applied to the soil. Ditching and earthing up can effectively ensure the growth and development of secondary roots, prevent lodging and reduce basal branching below the cotyledon node.

7. Timely irrigation: Sunflower irrigation uses the furrow irrigation method. Generally, for varieties with a plant height of 1.5 m, the first watering should be done at the bud stage, the second at the early flowering stage, and the third at the grain-filling stage. For varieties with a plant height of about 2 m, the first watering is done 4-5 days before flowering (in case of severe drought, irrigation is advanced), the second 6-7 days after the first watering, and the third at the grain-filling stage.

8. Pollination management: Sunflowers have a low seed-setting rate from self-pollination and a high seed-setting rate from cross-pollination. During cultivation, artificial supplementary pollination should be carried out in time, using methods such as pairing flower heads, powder puffs and cotton gloves to transfer pollen, or collecting pollen from the male parent and gently applying it to the stigma of the female parent with a small brush. Pollination should be carried out 3-4 times during the full bloom period.