Watermelon planting methods and management techniques

It is the hot summer now. When the temperature rises, many friends have no appetite. When it comes to fruits, they usually choose fresh and refreshing watermelon. There are also many users who grow watermelons in our country. Let’s learn about watermelon planting methods and management techniques.

1. Planting time

The sowing time of watermelon is influenced by both the characteristics of the variety and the climate temperature.

In terms of varieties, early-maturing varieties are planned to be launched in early July, and it is recommended to be sown in mid-to-late March. For mid-to-late maturing varieties scheduled to be launched in late July to mid-August, it is recommended to sow in mid-to-late April. For autumn watermelons that are planned to be on the market in September or October, it is recommended to sow them from the end of June to mid-July.

In terms of climate and temperature, watermelon prefers a high temperature environment. The starting temperature for seed germination is 15°C, and the optimal germination temperature is 25-28°C. Root growth requires a minimum temperature of 15°C or above. The seedling development requires a minimum temperature of 22°C or above. The flowering and fruiting period requires a minimum temperature of over 25°C, and a large temperature difference between day and night is required to accumulate sugar.

The earliest time for sowing in spring should be when the soil temperature reaches above 15°C to ensure that the seeds can germinate normally. To ensure uniform and rapid emergence, it is recommended to sow when the soil temperature reaches 18-20°C or above.

Avoid sowing when the soil temperature is below 15°C to prevent affecting seed germination and emergence. Consider the local climate characteristics and choose the appropriate sowing time to avoid adverse climatic conditions that affect the growth and development of watermelon.

2. Selection of planting plots

It prefers sandy soil or humus loam with strong permeability, and avoids using heavy, compacted, and low-lying land. The soil should be loose and fertile, with a high organic matter content, and avoid shallow and poor soil. Choose a well-ventilated, sunny site to ensure adequate light, and avoid areas with shade or insufficient light. The pH value of the soil should be slightly alkaline or neutral, avoiding soils that are too acidic or alkaline as well as soils with high salt content. The terrain should be higher for easy watering and drainage, and avoid areas with high groundwater levels, prone to waterlogging or poor drainage. The planting site should not have been planted with flowering and fruiting crops within 2-3 years. It is preferred to choose land that has not been planted with watermelon within 3-5 years, or the previous crop was a gramineous grain crop, to avoid repeated cropping and continuous cropping with melon and fruit crops.

3. Seed treatment

3-5 days before sowing, choose sunny weather and spread the seeds out to dry for 1-2 days. The purpose is to awaken the seeds, reduce residual pathogens on the surface and increase the germination rate.

Start soaking seeds 2-3 days before sowing. First, place the seeds in hot water at 50-55°C and stir constantly for about 15 minutes. Next, move the blanched seeds to warm water at 28-32°C and soak them for 6-8 hours to allow the seeds to fully absorb water. After soaking, scrub the seeds clean with clean water and then wrap them with moistened clean gauze. Place the wrapped seeds in a warm and humid environment at about 28°C to keep them warm and moist to promote germination. When most of the seeds have opened and turned white, it means that the seeds are ready for sowing and seedling raising.

4. Seeding management

Before sowing, make sure the seedbed or seedling pot is thoroughly watered, and sow after the water has penetrated. Place the white seeds with their sprouts facing upwards and evenly sow them on the seedbed. If broadcast sowing is chosen, thinning will be required afterwards. Cover the seeds with a thin layer of fine soil and then cover them with mulch to keep warm and retain moisture, thus promoting rapid germination of the seeds. From sowing to germination, try to maintain the temperature of the seedbed not lower than 25°C, and it is recommended to keep it at around 28-30°C.

When the watermelon seedlings grow 1-2 true leaves, gradually lower the temperature of the seedbed by 1-2°C per day and maintain it at 22-25°C. Cooling down helps seedlings adapt smoothly to low temperature environments and avoid excessive growth under high temperatures. This measure is beneficial to enhance the stress resistance of seedlings and improve the survival rate of later transplanting and planting.

5. Transplanting and Planting Management

When the watermelon seedlings are one month old, 10-15 cm tall, and have 3-4 true leaves and 1 heart, they are ready for transplanting. 5-7 days before transplanting, gradually increase ventilation, lower the temperature of the seedbed, and perform low-temperature hardening on the seedlings to promote strong root systems. The temperature should be lowered to 18-20°C during the day and 12-15°C at night, and fungicide should be sprayed 3-5 days before transplanting to prevent diseases. Water the seedlings before transplanting, cover the roots with soil, and grade the seedlings according to their size and strength. Choose a sunny day and transplant when the soil temperature reaches above 16-18°C. Before transplanting, dip the roots in carbendazim or microbial agents, or water the holes and roots after transplanting to reduce diseases and promote rapid rooting and seedling growth. About 1,000 early-maturing watermelon varieties are planted per acre, and about 800 medium- and late-maturing varieties. Avoid over-dense planting; reasonable density helps improve plant growth quality and yield.

6. Fertilizer management during the growth period

1. Base fertilizer: When preparing the land, apply more than 3,000 kg of decomposed farmyard manure or 200-400 kg of commercial organic fertilizer per mu. Apply 50-60 kg of balanced nitrogen, phosphorus and potassium triple compound fertilizer , or 15-20 kg of urea + 20-25 kg of potassium sulfate + 30-40 kg of superphosphate (in the north)/calcium magnesium phosphate fertilizer (in the south). When the soil is lacking in trace elements, apply 10-15 kg of trace fertilizer, or 1-2 kg of borax, zinc sulfate, and magnesium sulfate per mu. For plots of land with many soil diseases or underground pests, spread 80-100 kg of quicklime or 2-3 kg of phoxim granules or trichlorfon granules per mu.

2. Seedling-promoting fertilizer: When the water and fertilizer supply is sufficient and the growth is normal during the seedling stage, there is no need to apply additional seedling-promoting fertilizer. If slow growth, yellowing and weak seedlings occur, apply 2-3 kg of urea per mu 7-10 days after transplanting or after 2-3 leaves grow, or spray 0.3% urea water twice, with an interval of 7 days.

3. Vine-stretching fertilizer: A large amount of nitrogen, phosphorus and potassium is needed during the vine-stretching period (seedling height is about 15 cm, 5-6 leaves). Depending on the growth trend, apply 10-15 kg of balanced or high-nitrogen nitrogen, phosphorus and potassium compound fertilizer per mu. If conditions permit, urea water, potassium dihydrogen phosphate and boron-containing foliar fertilizer can be sprayed 1-2 times.

4. Melon-enlarging fertilizer: After the first young watermelon is firmly seated on the vine, begin to apply melon-enlarging fertilizer in batches. Combine with watering and apply twice. For the first time, when the young melon is the size of an egg, apply about 15 kg of balanced nitrogen, phosphorus and potassium compound fertilizer, or flush with 5-6 kg of balanced macro-element water-soluble fertilizer . The second time, when the young melon grows to the size of a bowl, apply 15-20 kg of high-potassium nitrogen, phosphorus and potassium compound fertilizer, or flush with 6-8 kg of high-potassium macro-element water-soluble fertilizer.

5. Foliar fertilizer: One week before flowering, spray potassium dihydrogen phosphate and boron-containing foliar fertilizer once to promote flower bud differentiation. 1-3 weeks after flowering, spray potassium dihydrogen phosphate, boron-containing and calcium-containing foliar fertilizers 1-2 times to enhance fruit quality. If leaves turn yellow and age prematurely in the middle and late stages of growth, use potassium dihydrogen phosphate combined with chelated iron, chelated magnesium, brassinolide and other foliar fertilizers and spray them twice, with an interval of 7-10 days. After the first batch of melons are ripe and harvested, spray 0.5% urea water and 0.3% potassium dihydrogen phosphate 1-2 times to quickly replenish nutrients, promote plant recovery, and continue flowering and bearing melons.

7. Watering management

Water thoroughly before planting to ensure the soil has adequate moisture before planting. After transplanting, water the seedlings in time to help them take root quickly. Keep the soil moist from the seedling stage to before flowering to promote root development. After the plants are planted and survive until they bloom and set fruit, reduce watering moderately and keep the soil moderately dry to promote root growth and flower bud differentiation. During the vine extension period, water the vines sufficiently to meet their water needs for vigorous growth. From the time the young melons are set until 7-10 days before harvest, water them frequently in small amounts to ensure that there is sufficient and stable water supply for the young melons to grow and develop. Avoid soil that is alternately dry and wet or drought and water shortage. After the watermelon enters the maturity period, control the moisture in time and reduce the water supply to promote sugar accumulation. One week before harvest, stop watering completely to improve the storage resistance and quality of the watermelon.

8. Pruning and artificial pollination

Timely pruning and trimming of vines: When the watermelon grows 8-10 leaves and the main vine reaches 40-50 cm in length, pruning and trimming should be done on a sunny afternoon, when the vines are relatively soft. Use the "three-vine pruning method", retain the main vine, select two strong branches from the 3rd to 5th nodes, and cut off all other side branches and vines.

Artificial assisted pollination in adverse weather conditions: If there is adverse weather such as rainy weather during the flowering period, which affects natural pollination, artificial assisted pollination can be used to increase the fruit set rate. Collect pollen from male flowers during the blooming season and apply the powder to the stigma of female flowers using a cotton swab. The best time for pollination is 8-9 am on a sunny day, and it needs to be postponed 1-2 hours in rainy weather.

9. Flower and fruit thinning and vigor control management

1. Thinning flowers and fruits

Remove excessive flowers and fruits promptly to avoid overburdening the plants and affecting the size and quality of the fruit. When thinning flowers, choose to keep the strong buds that bloom early and have a high fruit setting rate, and remove the buds that bloom late and have difficulty setting fruit. Keep 5-6 flowers on each strong branch and remove dense, weak and sickly flowers. When thinning the fruits, do it when the young melons grow to the size of an egg, select 3-4 melons on each strong branch, and remove the weak, deformed, and densely packed melons. When the young melons grow to the size of a bowl, select 1-2 melons with reasonable positions, correct shapes and healthy development from the melons selected in the early stage for each plant, giving priority to melons with the second and third female flowers.

2. Reasonable control of prosperity

Prevent excessive growth of watermelons, which may affect normal flowering and fruiting and result in reduced yields. For plants that grow vigorously, physical methods such as gently pinching the vines or topping and pinching can be used to control growth. If physical growth control is not effective, you can consider using chemical growth control drugs such as paclobutrazol, chlormequat, and mepiquat to spray 1-2 times.

In general, by learning the key points of watermelon planting and management techniques, we can optimize the growth of watermelon plants and improve fruit quality and yield. Farmers should flexibly apply these management measures according to the growth of the plants and field conditions during the watermelon planting process.