Humans are about 60 percent water; watermelons are about 90 percent. It makes sense, then, that these melon marvels are looked upon as refreshing, juicy summer treats. Listen to learn how to raise these remarkable fruit grown as vegetables.
This segment of The Old Farmer’s Almanac Garden Musings podcast series was written by George and Becky Lohmiller and is read by Heidi Stonehill, an Almanac editor.
What better way to top off a summer picnic or barbecue than with a juicy slice of sweet watermelon? Although watermelon may seem as traditionally American as apple pie, it is actually a native of Africa and is grown in 96 countries.
Watermelon is a tropical plant that requires high temperatures and a long growing season. Large varieties like ‘Georgia Rattlesnake’ (the kind sold in supermarkets) require at least 90 to 100 days to ripen. In areas where the growing season isn’t long enough to raise standard-size melons, the midget or icebox types are best. ‘Festival’, ‘Sugar Baby’, and the yellow-fleshed ‘Sunshine’ are three fast-growing melons that will produce 8- to 10-pound fruits in about 75 days.
For best growth, watermelons need daytime temperatures of 80°F (27°C) or more and warm nights. Gardeners in cold climates should start seeds indoors at least 4 weeks before they are to be set out. Watermelons are commonly grown in hills, because the soil stays warmer when mounded. Hills are usually fashioned 4 to 6 inches high and 2 feet across, and spaced 4 to 6 feet apart. Watermelons are gluttonous feeders and will benefit from plenty of rotted manure and 1⁄3 pound of 5-10-5 fertilizer spaded into each hill.
Allow two plants per hill, or if seeding directly, sow four to six seeds—evenly spaced and 1⁄2 inch deep. When seedlings appear, thin out all but the strongest two. Continue to feed the plants every 2 to 3 weeks with 5-10-5 fertilizer. Because watermelons are more than 90 percent water, they will require lots of irrigation, especially in the first few weeks and during dry spells. A thick covering of straw mulch will help conserve moisture and provide a cushion for the melons to rest on.
Ripe melons lose their shiny appearance and take on a dull look. The spot where the melon sits on the ground should be buttery yellow, and the tendril closest to the stem should be browning or dead. Once harvested, watermelons will keep 7 to 10 days, but we’ve got a hunch that a fresh melon from your garden won’t last nearly that long.