A few weeks ago I was able to visit with a colleague of mine down in south Georgia whose county produces over $12 million dollars in watermelons each year – roughly $6k per acre in profit. While I don’t necessarily recommend that you try to grow watermelons at quite that big of a scale, they can be a delicious addition to a home garden with proper care.
Watermelons need 8-10 hours of sunlight per day, so be sure to choose a sunny spot in your garden with ample space for their runners. A few months before planting, take a soil test and make the recommended amendments to soil pH and fertility. If you choose not to soil test, apply a fertilizer such as 10-10-10 to the garden at a rate of 3lbs per 100sq ft, tilling the fertilizer in to 6-8” deep.
Most watermelons grown in commercial operations are started from transplant, and I usually recommend that you do the same. You’ll need to start your watermelon seeds indoors about 4-5 weeks prior to the last frost. In this area, our last frost is typically in late March, so you’ll want to start seeds in February. To start your seeds, plant one or two per pot, then cover them lightly with soil. Keep them in a warm place with a minimum of 14 hours of light per day – you may need to invest in supplemental grow lights to meet this need. Keep the soil damp throughout the seedling growing period. Once soil temperatures are consistently 65-70 degrees, you can start hardening off the seedlings by placing them outside during the day, and bringing them inside at night. Repeat this for 2-3 days, and leave them out full-time on the 4th day. At this point, you can plant your transplants in your garden. In preparation for planting, create small hills in your soil with at least 8 ft of space on all sides. Plant one healthy transplant per hill, then compact the soil around it and mulch the garden to help conserve water and prevent weeds. The later in the season you plant your watermelon, the more pest problems you’ll have.
During the growing period, be sure to water the melons as needed to maintain soil moisture at a 6” depth – usually once or twice a week at one to two inches of water at a time to encourage root development. Gradually reduce watering as the fruits develop to improve flavor and reduce risk of fruit split. Overhead watering, such as sprinklers, will cause more problems with foliar diseases and pests, so drip irrigation at the base of the plants is recommended. Be sure to scout your crop regularly, looking at leaves and stems for signs of insect or disease damage. Foliar diseases, nematode and root problems, and insect pests are all common with watermelons. Identifying these problems early will help minimize damage and allow you to treat them effectively.
Watermelon is ready for harvest roughly 70-90 days after planting. The plant will develop the fruit closest to itself first, then develop the fruit further away in sequence. When the curly tendril at the stem is completely dry, the underside of the fruit is yellow, and the fruit has a dull thump sound when it’s tapped, the fruit is ready to harvest. Watermelon will stay fresh for 2 weeks if stored at temperatures below 60 degrees; and will 7-10 days at room temperature.
Watermelons are one of my favorite summer fruits, and I’m looking forward to this year’s harvest in June. If you have questions about watermelons or your home garden, please contact us at 706-359-3233 or uge3181@uga.edu.
