Watermelons are the fruit of summer, and their chilled fruit can provide juicy refreshment during a hot day. Instead of buying watermelon vines from a garden store or regional nursery, save yourself money by planting watermelon seeds. Give the watermelon seeds the basic care they need and you'll soon have rows of this hardy vine.
Prepare the gardening site once the outdoor temperatures reach a daytime low of 70 degrees Fahrenheit and a minimum evening temperature of 65 degrees Fahrenheit, according to Ohio State University. Break up the soil to a depth of 6 to 8 inches and mix in 3 inches of compost followed by a single application of an all-purpose garden fertilizer, like a 5-5-10 or 10-10-10 product.
Bury each watermelon seed an inch deep and 36 inches away from the next, according to the University of Illinois. If you're growing more than one row of the melons, separate the rows by approximately 10 feet.
Water the garden two times a day, in the morning and evening, or as needed to keep the top 3 to 4 inches of soil moist. The watermelon seeds will usually germinate within three weeks.
Reduce watering once the plants are 5 to 6 inches tall, after which the vines should only be watered when they show slight signs of drought stress like curling foliage or wilting. Watermelon plants have very deep root networks and rarely need watering unless it doesn't rain for extended periods of time, according to the University of Illinois.