15+ ORGANICALLY GROWN GIANT Ali Baba Watermelon Seeds Heirloom NON-GMO 30 LB Open Pollinated. Fruit Weight: Up to 30 Pounds. Plant Spacing: 12-18". Row Spacing: 6 row centers. Melons must not be planted until the SOIL temperature has warmed to 70-80 degrees F, since they thrive in heat. Start the plants indoors only 2-4 weeks before transplanting, since if the plants grow too large they have difficulty adjusting to the change. Set out 3-4 transplants per hill, selecting the strongest two when vines are 1'-2' long by cutting off the others. Watermelons are large vining plants that can take over an extensive garden space. They can be trellised, but use slings to support the developing fruit. Watermelon prefers light, loamy, fertile, deep, well-draining soil with a pH of 5.5-6.5. Add plenty of organic matter. Water plants amply until setting out, then water more sparingly. Mulch to prevent weed competition.