How to Grow Watermelons Successfully

Purchase watermelon seeds or transplants. Dependable varieties to consider include Charleston Gray, Madeira, Yellow Baby, Sweet Favorite, Jack of Hearts and Sunny’s Pride. Seeds stored longer than four years may not germinate; choose new seeds for a successful harvest. Avoid transplants that appear wilted, damaged or pot-bound.

Select a large area of the garden. Watermelon vines will spread considerably. Note that watermelons need at least eight hours of direct sunlight for optimal harvest. A shaded spot will result in stunted growth and a sub-par harvest.

Work the soil until it is loose and well-draining. Mix in well-rotted compost for best results. Watermelon vines prefer sandy soil, but the use of a plastic black film as mulch can provide successful results for those with clay soils. This is especially helpful for cooler climates, since the black plastic not only warms the soil but has the added benefit of superior protection against cold spells.

Build raised hills to plant watermelon seeds or transplants, spacing them about 7 feet apart. Each seed should be spaced 6 feet apart and sown 1 inch deep. If using transplants, carefully transfer each plant and space them 6 feet apart. Be careful not to destroy the delicate root system of the transplant. Water lightly but frequently until seedlings germinate. Avoid planting seeds or transplants until daytime temperatures reach a steady 70 to 85 degrees Fahrenheit. Otherwise, the crop is likely to fail.

Control weeds and pests if they occur. Common problems to be aware of include mites, cucumber beetles and aphids, all of which may be treated with an insecticide.

Harvest watermelons once they begins to ripen. The tendrils at the stem will become dry and brown, and the underside of the melons will turn from a green to a yellow. Attempt to penetrate with a fingernail to test for ripeness. With optimal weather and care, watermelons are typically ready for harvest within 75 days, but the time required to reach maturity varies by type.