The growth cycle of watermelon is generally divided into germination stage, seedling stage, vine stretching stage and fruiting stage (flowering and fruit setting stage, melon expansion stage and pulp turning stage).
1, and the germination period turns from white to true (true leaves are budding). At this time, the temperature should not be lower than 15℃, the suitable temperature is 25-28℃, and the growth period is 8- 12 days.
2. The suitable temperature is 22-25℃ and the growing period is 25-30 days. At this stage, the growth of stems and leaves is slow, mainly taking root growth as the core. If the soil moisture is high, low temperature will easily lead to root retting.
3. The vine extension period is from clumped trees to female flowers, the suitable temperature is 25-30℃, and the growth period is 15- 18 days. In the early stage of this stage, we should pay attention to nutrient growth, and at this time, the supply of water and fertilizer should be sufficient. Fertilization is mainly based on nitrogen fertilizer, with phosphorus and potassium fertilizer. After the male flowers open, attention should be paid to controlling seedlings, pruning vines, applying less water and fertilizer, and controlling the growth of stems and leaves.
4. The flowering and fruit-setting period is from female flower opening to fruit depilation (fruit-setting period), and the suitable temperature is 25-30℃, and the temperature should not be lower than 18℃. This stage is the transition from vegetative growth to reproductive growth, and it is necessary to control water and fertilizer to prevent falling flowers and fruits. Because watermelon is a half-day flower, it only blooms in the morning, and the cycle is only 4-5 days. If you choose artificial pollination, the male flowers that just opened in the morning should pollinate the female flowers. Attention should be paid to pollination, and the stigma of female flowers should be evenly coated to avoid producing deformed melons. You can also choose bumblebee pollination, which saves effort.
5. The swelling period of melon is from fruit depilation to fixed size, and the suitable temperature is about 30℃. At this stage, the fruit expands rapidly and needs water and fertilizer most, which can be supplied by large water and fertilizer. At this time, the fertilizer should be mainly phosphorus and potassium fertilizer with nitrogen fertilizer.
6. The deadline is from fixed investment to maturity, about ten days. At this time, there is less water to maintain the quality of fruit and promote the accumulation of sugar. The temperature difference between day and night should be appropriately increased from the expansion stage to the maturity stage to promote the accumulation of sugar in fruit and improve the quality of fruit.