When the watermelon is ripe, the curly tendril on the vine will dry up and turn brown and the white spot on the bottom of the watermelon will turn yellow. The watermelon will also lose its shine and become dull-looking.
The seeds could be infected, which means they will produce diseased plants.
While you can use seeds that have been collected from a watermelon that has been purchased from a store or local vendor, there is no way to tell from the watermelon whether or not it has been cross pollinated. So, the watermelons that grow from the seeds may be different from the watermelon you bought. [3] X Research source
Seeds can be collected when the watermelon is eaten or you can cut the watermelon open and pick the seeds out by hand.
Dry them in an area that is slightly warmer than room temperature and has good air circulation, like the top of your refrigerator. Do not expose the seeds to direct sunlight.
The seeds can be stored for up to five years.
