I made a really big mistake, and picked one of my watermelons way too soon. I had read that a sign it is ready is if it breaks away from the stem with very little effort. I guess I proved that tip wrong, and with disastrous consequences (hey, you’d be upset too if you just wasted a huge percentage of your watermelon crop). I also thumped it and thought it sounded right, but I’m apparently not very proficient at distinguishing the subtleties of melon sounds.
The exterior on the ill-fated watermelon was darker and more uniform than the ones here in the picture.
Does anyone have any better advice? I obviously need to wait longer, but how will I know? And how quickly do they get overripe?