Watermelons in a Pot in Zone 6

When you think of watermelon plants (Citrullus lanatus), you probably envision monster vines rambling through a garden patch -- not exactly the best match for container planting. New bush varieties, though, have an upright form and short vines, making them a suitable choice for growing in pots. Watermelons need a long, warm summer with at least 75 to 90 sunny days. Gardeners in U.S. Department of Agriculture plant hardiness zone 6 should have no trouble growing watermelon.

Although compact watermelon varieties take up less room than standard types, they still benefit from a large growing environment. Select a pot that can hold at least 5 gallons of potting mix -- more is even better. Old whiskey barrels, large clay pots or plastic grow boxes all work well as long as they are large enough and have adequate holes for drainage. Plastic pots don't dry out as quickly as clay pots, and they're lightweight, so they're easier to move. Fill the pots with a lightweight potting mix. Don't use garden soil, which often contains pathogens and doesn't drain well in pots.

Watermelons grow best at temperatures between 75 and 85 degrees Fahrenheit --and they don't tolerate frost. Plant them outdoors in your pots only after sunny weather has arrived -- typically between May 1 and May 20 in USDA zone 6. Moisten the potting mix before you plant the watermelons. Although zone 6 has an adequate growing season for watermelons, you can start the plants indoors three to four weeks before you plant them outdoors. Watermelons don't transplant well, so plant them in peat pots. Keep them warm and moisten the soil frequently. Place the peat pots directly in the larger pots.

Although watermelons grown in pots suffer fewer weeds, diseases and insect problems, they need some extra care in other areas. Water and fertilizer leach quickly out of the pots. Water the melons several times each week, or as needed to keep the soil moist 3/4 inch below the soil surface. Fertilize with a liquid fertilizer every two to three weeks, at a rate of 1 tablespoon per gallon of water or according to package directions. Another option is to use coated, time-release fertilizers. Apply these at a rate of 1 tablespoon per gallon of potting soil or according to package directions.

A large part of your success in growing watermelons depends on picking the right variety. Although gardeners in USDA zone 6 have reasonably long growing seasons, stick with varieties that mature within 75 to 80 days. Choose a compact variety that stays small. Try "Bush Sugar Baby" (Citrullus lanatus "Bush Sugar Baby"), which matures within 80 days and grows only 3 1/2 feet tall, or "Garden Baby" (Citrullus lanatus "Garden Baby"), a compact variety that matures within 78 days.