Watermelons are greedy. They need a lot of room to spread, a lot of water, good drainage, lots of sunlight and lots of nutrients. Despite all these needs, they are very easy to grow. Watermelons grow from seed. However, don’t use seed out of melons you bought because they probably hybrids which are special crosses that don’t grow true to type.
Watermelons are heavy feeders. Therefore you need to prepare soil adding compost or rotted manure. The pH of the soil should be 6-6.8, but the plants can also tolerate a pH as low as 5. Work the compost or organic slow-release fertilizer into the top soil. Then mound the soil into small hills spaced about 100 cm apart. If you can, try to cover the hills with black plastic to control weeds, maintain soil moisture and speed growth. Plant the watermelon seeds 2.5 cm deep in each hill. When seedlings sprout, thin them to only two plants per hill.
Caring for the plants
Watermelon vines bear female and male flowers. Therefore, some of the male flowers which appear first will fall off shortly after they open. The female flowers which blossom about a week later have a small swelling at the base of the flower. These stay on the vine to bear fruit.
Get rid of weeds before the vines start running because it will be difficult to tackle a weed problem at a later stage without crushing the watermelon plant. You ca also mulch the soil under the vines to help suppress weeds and slow moisture evaporation.
To keep the vines healthy , you need ensure there’s enough water. The plants are very sensitive to drought especially from planting time to when fruits start to form. However, you need to avoid overhead watering. Keep the soil consistently moist, but not waterlogged, which will kill plants. Therefore, try to water early in the morning so that the leaves can dry throughout the day. Drip irrigation delivers water directly to soil, helping prevent possible spread of fungal diseases among wet foliage. It’s normal for leaves to wilt under the hot sun. However, they shouldn’t stay like that into the evening.
Watermelons need to keep ripening from direct contact with soil to prevent rot and protect fruit from pests. To do this, place the fruit on a bed of straw or cardboard when it’s about the size of a softball. Avoid light-reflecting surfaces such as aluminum foil which can concentrate heat and speed up ripening.
If you’re using fertilizer, use a fertilizer with more nitrogen than phosphorus and potassium during the period between planting and when the first flowers open. Once flowering begins, use a fertilizer with less nitrogen and more phosphorus and potassium.
Some people believe that pinching shoots as watermelons start to ripen causes the plant to ripen well. However, the vine’s leaves produce the sugars that sweeten the watermelon. So, reducing the total number of leaves available for sugar production by trimming actually lessens the sweetness of the watermelon.
Approximately one week before a melon is ripe, only water to keep the vines from wilting. Too much water will reduces sweetness. Watermelons mature within about 80 to 100 days. You’ll know they are ready when they easily break away from the vine when twisted. If you try to pick a watermelon and it doesn’t twist off easily, it probably isn’t ready for harvest yet. Another sign that the melon is ripe is when the underside changes color from white to rich yellow.