BLUE SPRINGS, Mo. — Most plants in the vegetable garden need just a few square feet of space to grow well. Members of the squash family, called cucurbits, are the exception.
Available space may be part of the reason most American gardeners limit their production of cucurbits to cucumbers, zucchini and yellow squash, but a University of Missouri Extension horticulturist encourages gardeners with ample space to consider including at least one more member of this family.
“Watermelons are a fun and rewarding crop for the home garden,” said Marlin Bates.
Gardeners commonly build up hills where watermelons will be planted to allow for warmer soil conditions and better drainage.
“Drainage is particularly important, especially in gardens with heavier soils, because watermelons prefer sandy-loam soils that are very well-drained,” Bates said.
In addition, planting melons on hills helps ensure that water is reaching the root zone of the plants later in the season, when extensive vine growth tends to hide the plants’ crown on level planting beds, he said.
You can transplant watermelons into the garden, but it’s easiest to directly seed them into the hills. Each hill should be at least 3 or 4 inches above grade and 12 to 18 inches in diameter. Each hill should have about 64 square feet of clear space around it. For multiple hills, space them 8 feet apart. Plant four or five seeds per hill. After germination, select the two best-performing seedlings to grow on, removing the others.
Like all other cucurbits, watermelons produce separate male and female flowers. The first flush of flowers is typically all male, so don’t expect fruit from them.
“Their purpose is to attract pollinators and to provide pollen when female flowers are open,” Bates said.
Pollinators are critical to ensure that the female flowers get pollinated. “Research indicates that to get fully pollinated and to produce a good fruit, female watermelon flowers will need to be visited by a pollinator between six and 12 times,” he said.
The key to developing high-quality fruit is ensuring good vegetative growth early on.
“When the plants begin to send out runners, a light application of nitrogen will help to create this vegetative growth,” he said.
Apply nitrogen at this stage at a rate of a half-pound per 1,000 square feet. “Don’t apply fertilizer after the runner stage, as it can delay flowering or cause the fruit to crack after it sets. A watermelon patch that has good cover will set and ripen more fruit and provide its own weed control.”
Watermelons can be a great addition to spacious home gardens, but gardeners with limited space can still include watermelons in their plantings.
“Vining crops are easy to train onto a vertical plane,” Bates said. “Just be sure that the scaffold you’ll be training the plant onto is sturdy enough to hold the plant along with its fruit. The developing melons will need to be tethered to the trellis with a slinglike support made from a material that is quick to dry.”