How should the newest watermelon seeds be planted for the best results?

Watermelon is also known as summer melon, cold melon, etc. It is an annual trailing vine of the genus Citrullus in the Cucurbitaceae family. Its original species may have come from Africa, and it has long been widely cultivated from the tropics to the temperate zones of the world. It is widely cultivated throughout China, with a great many varieties, and the most famous places include Xinjiang, Lanzhou in Gansu, Dezhou in Shandong, and Liyang in Jiangsu. Now let us take a look together at how watermelon seeds should be planted for the best results!

Seed Selection

Before sowing watermelon seeds, select them carefully according to the characteristics of each variety, removing shriveled seeds, insect-damaged seeds, broken seeds, moldy seeds and other debris. Then sun them for 1 to 2 noons, with a thickness not exceeding 1 cm, turning them about once every 2 hours so they receive light evenly, in order to enhance seed vigor and improve germination energy and germination rate. Before sowing, a germination test should first be done, and the sowing rate should be determined according to the seed germination rate. For direct sowing, generally 50 to 80 grams of seed are needed per mu.

Disinfection and Sterilization

1. Hot water seed soaking: Hot water seed soaking can prevent watermelon mosaic virus disease. 3 to 4 days before sowing watermelon seeds, place the selected watermelon seeds in a clay pot, and soak them in warm water at about 55°C made by mixing 2 parts boiling water with 1 part cold water. After the seeds are placed in the warm water, stir continuously, and stop stirring when the water temperature drops to 30°C. Keep them soaked at that temperature for 3 to 5 hours, then wash off the mucus on the seed coat.

2. High-temperature scalding of seeds: High-temperature scalding of seeds can kill pathogenic bacteria on the seed surface. Put equal amounts of cold water and boiling water into two containers, with the water amount being 3 times the amount of seeds. First pour the selected seeds into the boiling water and stir quickly for 4 to 5 seconds, then immediately pour in the cold water from the other container, and continue stirring until the water temperature drops to 30°C, then stop stirring and soak the seeds for 3 to 5 hours. Note that the scalding must be done quickly, and the scalding time should not be too long, so as not to affect the seed germination rate.

3. Chemical disinfection: You can soak the seeds in 100 times diluted formalin for 30 minutes, or in a 2 to 4% bleaching powder solution for 30 to 60 minutes, or in a 500 times diluted 50% carbendazim solution for 1 hour, or in a 10% trisodium phosphate solution for 20 minutes, or in a 500 times diluted 50% amobam aqueous solution for 0.5 to 1 hour, or in a 500 times diluted 10% antibacterial agent 401 for 30 minutes.

Seed Soaking and Germination

1. Seed soaking: Seed soaking can speed up the water absorption rate of seeds and shorten the time for germination and emergence. The soaking time varies with water temperature, seed size, seed coat thickness, etc. When the water temperature is high, the seeds are small, and the seed coat is thin, the soaking time should be shorter. Soaking in cold water for generally 6 to 10 hours is suitable, while soaking in warm water at about 25 to 30°C for 3 to 6 hours is enough. After soaking, rinse the seeds with clean water and rub them repeatedly to wash off the sticky material on the surface, so as to benefit seed germination.

2. Germination: Germination ensures that after the seeds have absorbed enough water, the nutrients in the seeds are quickly decomposed and transported to supply the growth needs of the young embryo, so that under artificially controlled conditions the seeds can be promoted to germinate quickly. First rinse the soaked seeds with clean water, then wipe off the excess water attached to the seeds with a cloth. A small amount of seeds can be wrapped in a wet cloth and placed in a clay pot to germinate at 28 to 30°C, while a large amount of seeds is better germinated by the cloth-roll method.

Sowing Management

1. Seedbed preparation: For the watermelon seedbed, choose a plot that is sheltered from the wind and faces the sun, with high and dry terrain and convenient management. For raising early-spring watermelon seedlings, it should be done in a greenhouse or plastic tunnel. To keep warm, electric heating wires can be laid to raise the soil temperature, and a small arched shed can be added over the seedbed. For raising watermelon seedlings for late-autumn delayed cultivation, a shade shed should be built, and attention should be paid to preventing erosion by heavy rain.

2. Soil preparation: The nutrient soil for the watermelon seedbed should be loose, free of pests and diseases, fertilized with nitrogen, phosphorus and potassium in proportion, and slightly sticky. You can evenly mix 6 parts paddy field topsoil, 3 parts decomposed barnyard manure, and 1 part plant ash, and add 5 kilograms of decomposed chicken and duck manure per cubic meter of soil. Both soil and fertilizer should be crushed and sieved, kept granular, then mixed thoroughly with an appropriate amount of water, and piled for 1 to 2 months before sowing.

3. Timely sowing: Early-maturing watermelons are sown from mid-December of the previous year to late March, mid-maturing watermelons are sown from April to June, and late-autumn delayed watermelons are sown in mid-to-late July. In the afternoon of the day before sowing, water the nutrient pots thoroughly. When sowing, place the seeds with sprouted tips flat in the nutrient pots, 1 seed per pot, cover with fine soil 1 cm thick, and cover with plastic film.

4. Seedling stage management

① Temperature management: After the watermelon seeds are sown, the daytime temperature in the bed should be controlled at 28 to 35°C and the nighttime temperature at 20 to 25°C. After 80% of the seeds break through the soil and emerge, keep it at 20 to 25°C during the day and 15 to 18°C at night. After the first true leaf appears, keep it at 25 to 28°C during the day. Begin hardening the seedlings 1 week before transplanting.

② Water management: Generally, do not water again before the watermelon seedlings emerge. During the cotyledon stage, watering should be controlled, keeping the surface dry and wet alternately, mainly preserving soil moisture. After the true leaves unfold, the amount of watering can be increased. Water in the morning on sunny days, and after watering loosen the surface soil to preserve moisture. Do not water on cloudy days, and also pay attention to uncovering the film for ventilation.