When will the latest sunflowers be sown?

Sunflowers can be planted in all seasons, usually in summer and winter, with a flowering period of more than two weeks. in addition to being similar to the sun in appearance, bright and generous flowers are very suitable for ornamental decorations, and the seeds are of more economic value. it can not only be made into beloved sunflower seeds, but also extract high-grade edible sunflower oil with low cholesterol. Let's take a look at when sunflowers will be sown.

Sowing time of sunflower

The sowing time of sunflower is from March to April, the suitable temperature for sowing is 18: 25 ℃, and the sunflower sprouts about 5-7 days after sowing. The basic principle of sowing date selection is to sow early or late appropriately according to the occurrence law of saline-alkali, so that the seedlings can avoid the harm of saline-alkali. Spring sowing or summer sowing according to the growth period of the variety. Adjust the sowing date according to the disease law to avoid the disease-prone season. The sowing date was adjusted according to the growth characteristics to avoid the high temperature of more than 28 ℃ during flowering and filling period. The sowing method is on demand, the soil cover is about 1 cm, and the flowers are about 50-80 days after sowing, which varies slightly according to different varieties.

The growing environment of sunflower

1. Temperature: sunflower is a temperature-loving and cold-tolerant crop, which has strong adaptability to temperature and strong tolerance to low temperature. Seeds with stable local temperature begin to germinate when the local temperature is more than 2 ℃, and can germinate and take root at 4-5 ℃. When the ground temperature reaches 8-10 ℃, it can meet the needs of seed germination and emergence. During the whole growth process, sunflowers can grow normally as long as the temperature is not lower than 10 ℃.

2. Water: sunflower is a crop that consumes a lot of water, with tall plants, many leaves and dense leaves, and its water absorption is 1.74 times that of corn, but because its growth and development is synchronized with local rain and heat, the contradiction between water supply and demand is not prominent. there are great differences in water requirements at different growth stages. There is not much water from sowing to budding, the peak of water demand from budding to flowering, and more water from flowering to maturity.

3. Light: sunflower is a short-day crop, which is not very sensitive to sunlight. Like plenty of sunlight, its seedlings, leaves and disk have a strong phototropism. Sufficient sunshine and strong seedlings can prevent overgrowth. Sufficient sunshine in the middle growth stage can promote the vigorous growth of stems and leaves, normal flowering and pollination, and improve the seed setting rate. In the later stage of growth, the sunshine is sufficient, and the grain is full.

4. Soil: sunflowers have low requirements for soil and can grow on all kinds of soils, from fertile soil to dry land, barren and saline-alkali land. It not only has strong saline-alkali tolerance, but also has salt absorption ability. At the same time, sunflower has developed root system and strong drought resistance. Moreover, the root and stem aerosol tissue of sunflower is well developed, which is very resistant to waterlogging.

The growth cycle of sunflower

1. Seedling stage: sunflower is called seedling stage from emergence to budding, which generally takes 35-50 days and 28-35 days for summer sowing. This period is the stage of leaf, flower primordium formation and floret differentiation. Sunflower seedling stage is the strongest stage of drought resistance, the aboveground growth is slow, the underground root grows faster, and quickly forms a strong root system.

2. Budding period: it takes about 20 days for sunflower to blossom from budding to flowering. It is the most exuberant stage in life for both vegetative and reproductive growth. During this period, the largest amount of fertilizer and water is needed, accounting for about 4050% of the total amount of fertilizer and water. If the demand for water and fertilizer can not be met in time, the output will be seriously affected.

3. Flowering period: it usually takes 6-9 days for a sunflower disk to bloom from ligulate flower to tubular flower, and blossoms from the second day to the fifth day. Most of them bloom at 4: 6 a.m. and the unpollinated branches can be kept for 7-10 days the next morning. However, the seed setting rate of self-pollination is only about 3%, and the seed setting rate of cross-pollination is high.

4. Maturity: sunflower maturity refers to the stage from flowering to maturity, with 25-55 days of spring sowing and 25-40 days of summer sowing, with differences among different varieties. About 15 days after flowering and pollination shield is the stage of grain formation. Sunflower maturity needs sunny weather, large diurnal liquid temperature difference and suitable soil moisture.