Tips for Growing Watermelons

Watermelon belongs to the cucurbit family, which includes all vining yellow-flowered vegetables.

Watermelons, a warm-weather crop, grow best in the hotter regions of the United States. In the cooler Northern region, watermelons require a little more effort to produce. Regardless of where it's grown, a crop of watermelons requires a generous amount of space and sunshine. Choose a smaller hybrid variety if space is limited.

Soil Requirements

Watermelons thrive in sandy loam soil in the neutral -- pH of 7.0 -- or slightly alkaline range. Since a light sandy soil warms quickly in the spring, it's the best soil for growing in Northern gardens. If your soil consists of heavy clay, amend it with peat, compost or rotted manure. If you're not sure what kind of soil you have, your extension service can perform a soil test for you.

Planting Watermelon Seeds

The long, hot summers of the Western and Southern states make it easy to start watermelon seeds directly in the garden soil after all danger of frost has passed. Seeds rot if planted in soil that is under 60 degrees Fahrenheit. A temperature of 70 degrees Fahrenheit is recommended. Form hills about 8 to 10 inches high and plant four to six seeds 1 inch deep in a circle around the hill. Space the hills five inches apart in each row. Space the rows seven to 10 feet apart. Once the seedlings appear fully established, thin them to the three best plants per hill.

Planting Watermelon Seedlings

In the cooler Northern states, the sunny days and shorter summer season require different methods for growing watermelons. Transplants give you a head start on the growing season. You can purchase them at your garden center or start them indoors three weeks before the last frost. Choose early varieties such as Golden Crown, Sugar Baby, Yellow Baby and Yellow Doll. Plant outside after all danger of frost. It takes 70 to 75 days from the time of planting to harvest.

Tips for Seeds or Seedlings

Whether you plant seeds or seedlings, this method gives your watermelons a boost: Lay black plastic mulch over the prepared planting area. When you're ready to plant the seeds or transplants, cut a slit in the plastic mulch and plant. The black plastic mulch warms the ground quickly and keeps it warm. It also helps to deter weeds. This method is best for producing a good crop of watermelons in the cooler Northern region of the country.

Growing Watermelons on a Trellis

If you lack the ground space for growing watermelons, try growing them on a trellis. Choose a smaller variety of watermelon for this method. Space the melons three feet apart. Make slings to support each melon out of material that dries quickly such as cheesecloth, old nylon stockings or other netting. Tie the slings to the trellis.

Choosing Seeds to Grow

Saving seeds from this year's watermelon harvest to plant next year is not recommended. Many of the watermelons are hybrids that can produce an undesirable crop. For best results, choose a watermelon cultivar recommended for your area.

References

• University of Illinois Extension: Watermelon
• Purdue University Extension; Growing Cucumbers, Melons, Squash, Pumpkins and Gourds; B. Rosie Lerner, et al.
• University of Arizona Extension: Melons