Milk and watermelon may not be a common combination in the diet, but they are good friends in the garden. Milk can be used during two stages of watermelon gardening. The first application is to soak the seeds in milk to help them germinate faster -- a real plus if you are in colder areas with short summers. Later, milk can also be used to spray mature vines to help prevent powdery mildew, a common watermelon fungal disease.
Work a good 2 to 3 inches of compost into the soil of the garden bed after the soil has thawed in early spring. The garden bed must be in a sunny position.
Work the garden bed into mounds around 12 inches across and 12 inches high, spaced 4 to 5 feet apart. There should be one mound for each plant you intend to plant.
Cover each mound with black plastic to around 1 foot out from the base of the mound. Cover the edges of the black plastic with soil to keep it in position. The plastic will help the soil warm faster and keep weeds at bay as well.
Heat 1 cup of milk on the stove so that it is just warm and transfer it to a plastic container. Place your watermelon seeds into the warm milk and leave the container for 24 hours in a cool position in the house. You should soak about 3 to 4 times as many seeds as you want plants to guarantee germination and they should be soaked after the last frost date has passed.
Remove seeds from the milk after 24 hours. They should be bloated and have lightened in color from absorbing the milk. The milk provides them with nourishment speeds up germination time.
Cut a slit into the top of the plastic on each mound and plant 3 to 4 seeds 1/2 inch deep in the prepared soil. Water seeds heavily. Soak bi-weekly to encourage deep roots.
Thin plants to the strongest seedling about two weeks after germination. Cut the other seedlings off at the base, rather than pull them out to avoid disturbing the strongest seedlings' roots.
Mix 1 part milk to 9 parts water in a spray bottle and spray vines weekly to ward off powdery mildew.
Reduce watering to once a week after fruit has set on the vine, and even less if there has been rainfall. Excess water when the vine is fruiting promotes a less flavorful melon.
Harvest watermelons when the rind is hard and is just starting to yellow on the ground side. This should be within 12 to 16 weeks after planting. If you want an ongoing supply of watermelons throughout the summer, stagger planting dates.