First, examine the surface. A watermelon needs to be nicely shaped and symmetrical. Examine its outer surface carefully before you purchase. The surface should be green, without cracks or bruises. If the watermelon has stripes on its surface, they can also provide you with information about its ripeness. A ripe watermelon needs to have nearly uniform surface. If the stripes stand out too much and their color differs sharply from the color of the rest of the outer surface, the watermelon is still unripe. Press the surface gently. If you feel a soft spot, the watermelon is probably overly ripe and will soon be unsuitable to eat. Avoid watermelons that have soft or rotting spots on their surface or deep gashes, pits, fissures or holes. Some minor scratches are okay, however. After all, the purpose of that thick rind is to protect the delicious contents inside. Ripe watermelons should also be dark green in color. The rind should not be soft or give to pressure, such as a ripe cantaloupe or other melon; it should be firm and smooth.The tough rind should protect the juicy fruit inside.
What about picking a melon fresh from the field? How do you know which ones are ready? Having grown up on a farm where we went straight to the field to get our melons, I remember some tips my daddy gave me. Here are a few things that indicate that your watermelon is ready to harvest:
First, the tendrils near where the watermelon meets the stem, which are normally bright green, will have turned brown. Second, the surface of the watermelon will have gone from shiny to dull. Third, the side of the melon that rests on the soil will have turned from green to yellow, leaving a "sunspot."
Preparing the melon for the table:
How to Slice Watermelon (You can also locate these instructions on page 165 of "A Pinch of This... A Smidgen of That" Cookbook.)