The Growing Zones for Watermelons

Growing Zones

• Watermelons are hardy in USDA Zone 3 to 9, as listed by Lizz Shepherd in "The Complete Guide to Growing Vegetables, Flowers, Fruits and Herbs from Containers". Being native to Africa, watermelons are poorly adapted to low temperatures and frost, and they require a long, hot growing season for optimal growth. Ideal daytime temperatures are between 70 to 80 degrees, with nighttime temperatures of 65 to 70 degrees. Watermelons need a lot of water but they grow best in dry areas, as this reduces chances of foliar disorders.

Planting Time

• Start watermelon plants with seeds or transplants two to three weeks after the last spring frost in the area. If you're starting seed indoor, plant in peat or paper pots six weeks before last expected frost. Consistently hot temperatures of 90 degrees or more leads to blossom drop, and regular nighttime temperatures of 50 degrees or lower reduces fruit flavor. In areas with cooler or shorter growing seasons, use smaller-sized, quick-harvesting varieties.

Planting Suggestions

• Watermelons grow on large, sprawling vines that require adequate room to spread. Plant the seeds at a depth of 1 inch on mounds. Space the mounds at least 6 feet apart with 7 to 10 feet between the rows. Thin the seedlings by selecting the healthiest three plants on each mound. When using seedless watermelons, it is important to grow a standard-seed variety for effective pollination and fruit set.

Irrigation

• Watermelon vines have a high water requirement; watermelons have a water content of 95 percent. Regular irrigation assures rapid growth. Apply enough water to keep the soil moist until the fruit reaches mature size. Reduce watering at this point until the fruit ripens. Apply mulch, as this not only helps to conserve soil moisture but also keeps weeds out.