Watermelon, like other melons, are often started indoors to give the gardener a start on the growing season for their area. Watermelon seeds can be planted directly in the ground once the temperature of the soil has reached at least 65 degrees Fahrenheit. The length of time to maturity of the fruit will depend on the variety of the watermelon, but most are ready to harvest in 85 days or less.
Create rows in the garden, 1 inch deep and 5 to 6 feet apart.
Place two to three watermelon seeds together in a group, spacing each group around 18 to 24 inches apart.
Cover the seeds with 1 inch of soil.
Thin the watermelon seedlings to the best plant in each group after the second set of leaves appear on the seedlings.