Stage 1: Germination
The first stage of watermelon growth occurs when seeds are placed in the soil. When soil temperatures exceed 65 degrees Fahrenheit, bury the seed a depth of four times its width. Once planted you can see the growth of the stems and roots. In three to twelve days, the hypocotyl pushes the first two leaves, or embryonic leaves, above the surface of the soil.
Stage 2: Vining
Five to ten days after germination, the first set of true leaves emerge from the stem. These leaves are capable of photosynthesis. A vine of about 1 foot long grows out and large lobed leaves begin to form. This runner will continue to grow until it reaches about 12 feet in length. About one month after a watermelon plant sends out its first vine, several more vines will begin to grow. Leaves form on all the vines and begin to grow larger. Provide watermelon seedlings with one to two inches of water per week.
Stage 3:Flowering
About two weeks after a plant sends out most of its runners, watermelon produces male and female flowers. The male flowers develop first. They provide pollen, but do not produce fruit. The female flowers form shortly after the male flowers. Watermelon flowers only last for one day so there must be an adequate number of bees and other pollinators in the area when the flowers are viable.
Stage 4:Fruiting
Once pollinated, female watermelon flowers begin to produce fruit. Tiny green balls begin to swell beneath the blossoms. Once the watermelon plants begin to fruit, provide at least one inch of water per week until harvest.
Depending on the watermelon variety, the fruit takes up to one month to fully mature. It can be difficult to know when the melons are fully ripe, especially at the beginning of the season. Some signs are the tendrils on the vine changing from green to brown, the spot on the ground where the melon lay changes from white to yellow and the sound made when you thump the watermelon changes to a hollow sound.
