How to Grow Watermelons

Select the type of watermelon you want to grow. Watermelons vary greatly in size, ranging from about 1.3 kg to 32 kg, and the flesh can be either red or yellow. Varieties like Jubilee, Charleston Grey, and Congo produce large, oval-shaped fruits, while Sugar Baby and Ice Box varieties yield smaller, rounder fruits.

• Decide whether you will sow seeds or transplant seedlings. Watermelon seeds only germinate in temperatures above 21°C. If you live in a colder region, it’s best to start the seeds indoors a few weeks before the last frost so the seedlings can be ready for planting. Otherwise, sow the seeds directly in the soil after the cold season when the temperature is consistently above 21°C.
• Watermelon seeds and seedlings are available at nurseries in early spring.

Select a planting location. Watermelon plants need at least 6 hours of sunlight daily. They grow into large, sprawling vines that take up a lot of space. Plant each watermelon in an area with dimensions of 1.2 meters by 1.8 meters, unless you are growing a miniature variety.

Till the soil. Use a plow to loosen the entire soil layer and break up large clumps. Remove weeds or bury them deep into the soil.

• Watermelons prefer rich, loamy soil that drains well. To test your soil's drainage, observe the surface after a heavy rainfall. If there are puddles of water, the drainage is insufficient.
• To enrich the soil, add fertilizer to the surface layer.
• Watermelons thrive in soil with a pH level between 6.0 and 6.8. Check the pH of your soil to ensure it is suitable for planting watermelons. If it’s not ideal, you can adjust it by adding amendments available at nurseries.

Create soil mounds. Use a tractor or hoe to form mounds of soil (shaped like small hills) for planting the seeds. Space the mounds 1.2 to 1.8 meters apart, depending on the size of your available land. Mounding the soil ensures good aeration for the roots, prevents waterlogging, and helps retain moisture during dry weather.

Sow the seeds. Create a flat, slightly concave surface at the top of each mound. Use your finger or a tool to make three to four holes in the soil, each about 2.5 cm deep. Place one to four seeds in each hole, then cover the holes with soil and lightly press the surface to ensure the seeds are fully covered, trapping moisture around them.

Observe the sprouting seeds. Seeds typically sprout and grow into seedlings within 7 to 10 days, depending on soil temperature and planting depth. Keep the soil around the seeds moist throughout the germination process; water gently so that moisture reaches the developing tiny roots.

• Once the seedlings have emerged, leave only the two healthiest plants to ensure they have enough space to grow.
• Do not let the soil dry out; water at least once per day.

Add mulch to each mound when the seedlings reach around 10 cm in height. You can use straw, burlap, or compost as mulch. Try to cover as close to the plant stem as possible to suppress weeds, retain moisture, and prevent the soil around the young roots from overheating in the sun.

Reduce watering when the plants begin to flower. After the flowers bloom, water the plants every three days if the soil appears dry. However, do not overwater, as watermelons have low water requirements.

• Keep the leaves and fruit dry. You can place the watermelon on a clean piece of wood, smooth stone, or brick, etc.
• On hot days, the leaves may wilt even if the soil remains moist. If you notice wilting leaves in the evening after a hot day, water deeply to reach the root zone.
• Enhance the sweetness of the watermelon by withholding water for a week before harvest. However, avoid doing this if the vines appear wilted. Once the fruit is harvested, return to your normal watering routine to support a second harvest.

Regularly remove weeds. Pay attention to weeding around the base of the plant, along the vine, and in front of the growing tendrils.

Ensure the watermelon is ripe. Under ideal growing conditions, watermelon reaches peak sweetness within four months in warm weather. Harvesting too early will result in less flavorful fruit.

• To check ripeness, gently tap the watermelon. A dull, deep sound indicates the fruit is ripe. Additionally, turn the watermelon over and look at the underside—ripe watermelons will have a light white or yellowish hue.
• If the curly tendril near the stem has dried out, this is also a sign that the watermelon is ready to be picked.

Cut the watermelon from the vine. Use a sharp knife or garden shears to cut the watermelon from the vine near the fruit. Freshly harvested watermelon can be stored for up to 10 days.