Watermelons are mostly water: over 90%. Despite that, the large fruits are full of nutrients and many vitamins. In the places of the world where it grows freely, it is often seen being eaten on beaches and in parks as a refreshing snack. The fruit is very low in calories and sodium. The origins of watermelon have been traced back to the deserts of southern Africa where it still grows wild.
Seeds can be sown direct but it is often better to start them off in pots under glass, especially in cooler climates. Plants need at least 80days of warm (above 21C or 70F) weather to grow well and produce fruit. Start seeds in 3-4 inch pots. then plant out in well-composted/manured soil. Watermelons hog space so plant 1 meter apart and then thin out as plants grow.
Watermelons take about 80 days to grow from when it is planted out. As this gets closer start to watch for when it becomes ripe. It is likely to be ripe If you see the stem leading to the fruit turning brown, the surface of the fruit going from shiny to dull, and if it gives off a dull hollow sound when knocked on.