How To Grow Jumbo Watermelons

Purchase watermelon seeds from either a specialized seed catalog or a local gardening center. Try to get a variety that is known to do well in your region. Recommended varieties include Carolina Cross as well as Charleston Gray, Crimson Sweet, Sunny’s Pride and Sweet Favorite. For region-specific recommendations, contact a local extension office.

Collect a soil sample from the area where you plan to grow the watermelon. Take it to a local extension office for soil testing. The results will include recommendations on how to improve the soil for optimal watermelon growth. Depending on the condition of your soil, you may need to add additional fertilizer, sand or lime.

Work improved soil until it becomes well-draining and loose. Add organic matter such as well-rotted manure or compost to the top layer of the soil. Sow four to five seeds one inch deep in hills. Water frequently to ensure soil remains moist for optimal germination. After seedlings develop, thin to one plant per hill. Note that each plant needs around 100 square feet of space for vines to grow and spread effectively.

Once the vines have reached approximately 15 feet long, cut off all but two melons for each vine. After the two melons mature to a weight of about 1 pound each, cut one of them off and leave the other one on the vine to grow for the remainder of the growing season to allow the vine to feed only one melon rather than two.

Weed as needed throughout the growing season. Continue weekly watering to prevent vines from drying up. Avoid watering to the extent that the ground becomes saturated, as too much water can cause the melon to crack. Look out for major diseases and treat with a fungicide if they do occur.

Protect the growing melon from intense sun by covering it with straw, which prevents rotting. Lay black plastic mulch under the melon and top with straw to create a bed for the growing fruit. Protection such as this is essential due to the unusually long growing season jumbo watermelons must undergo.

Harvest ripe watermelons by cutting off the fruit from the vine. Use gardening shears to accomplish this because pulling it off the vine may result in cracks, which allow disease to enter the melon. The bottom of the melon will turn from green to a pale yellow when ready for harvest. A deep yellow color on the underside indicates it is overripe. Jumbo watermelons are typically ready for harvest 130 days after sowing, although weather conditions and selected variety all play a determining role in harvest dates.