Watermelons is a summer fruit that originates from Africa. This tender, warm-season fruit needs temperatures of 65 to 80 degrees F and a long growing season to fully develop. When growing watermelon in a short growing season area, choose a variety that matures early. Seedless varieties are self-sterile hybrids. They are planted with a normal seed varieties so that they can cross pollinate and set fruit. Watermelons do not like their roots disturbed, so it is best to plant watermelon seeds directly into the garden.
Clear an area of weeds, grass and debris after the soil has warmed and spring frosts are over.
Loosen the soil to the depth of 6 inches with a shovel. Break up large dirt clods and remove large rocks from the soil. Spread a 1-inch layer of sand over the area to improve drainage. Add a 2-inch layer of peat moss to increase organic matter in the soil. Mix the soil amendments in and rake smooth.
Create 12-inch tall hills of earth placed 6 feet apart. Poke six holes in the hills 1-inch deep with your fingers. Drop a watermelon seed into each hole. Cover with soil and gently firm down.
Sprinkle the areas with water until it is 1 inch deep. Do not use a high pressure water stream since this may dislodge the watermelon seeds.
Pull up all but three of the strongest seedlings when they reach 4 inches tall. Leave the three best plants in the hill.