Direct sow 2 weeks after threat of frost has passed, or start indoors 1-2 weeks before last frost. Plant in full sun, and mulch in between the plants if possible. Watermelons enjoy hot temperatures and need only moderate water to set fruit. In fact, fruit are sweetest in dry seasons. These melons have a thin rind and are susceptible to cracking when ripe - so, when they reach the size of a soccer ball, check them often for peak ripeness.