A warm season vegetable, the watermelon grows well across the U.S. with care. Warm summer days and nights coupled with a long growing season produce large, juicy watermelons. Southern regions grow watermelons with ease; northern states must start seeds indoors to transplant outside when all danger of frost has passed. By starting seeds indoors, northern region gardeners can prolong the growing season, since many varieties take up to 85 days to mature.
Sunlight and Air
Watermelons thrive in locations that offer full sunlight. Air circulation is important to help prevent disease and fungal infections from occurring. Watermelons are often planted on small hills spaced 8 feet apart. The hill allows the plant to drape across the expanse. The watermelon also does well went planted in rows with a spacing of 2 to 4 feet.
The watermelon plant enjoys tilled soil to spread its ample root system in as it grows. Add abundant organic material at the time of planting to provide much-needed nutrients to the seeds or transplants. Leaf mulch, peat moss or aged manure work well. The watermelon prefers well-draining soil that is crumbly to the touch. It also prefers a planting site with ample humus. The daytime temperature should range from 70 to 80 degrees Fahrenheit when planting watermelons.
The watermelon requires ample water to survive. Water the plants deeply at least twice per week if no rainfall occurs. The soil around the watermelon plant should always feel moist to the touch. A soaker hose or drip irrigation system works well to water the root system of the plant deeply at a slow rate.
Once the watermelon plant appears and its foliage begins to spread, it will require a top dressing of either 5-5-5 or 10-10-10 general-purpose fertilizer. Apply 1 1/2 lbs. per 100 square feet of garden space to supply the needs of the plant with ample nutrients. The leaves of the water melon plant are sensitive to granulated fertilizers, so never allow the leaves to come into contact with the fertilizer. Water the fertilizer into the soil thoroughly, so the plants root system can easily absorb it. The plant will need to be fed again when blossoms appear.
The watermelon plant can benefit from an application of a liquid seaweed fertilizer when the foliage first appears and after flowering. Watermelons require ample potassium and phosphorus for melon production. Many areas are deficient in potassium and phosphorus. Perform a soil test to determine the deficiencies and then apply additional dressings of potassium and phosphorus fertilizer after flowering, as needed.