Watermelons that will not ripen!
I planted Black Diamond watermelons the middle of May. Now it is the first part of October and the vines are dying. I checked the watermelons and they are still not ripe! Size is good. What could possible be wrong? This has been going on for several years but I keep trying.
By this time the melons should be ripe. Thumping the watermelon doesn't always work. I for one can't hear any difference. A better way to tell if the watermelon is ripe is to look at physical characteristics. On the stem where the watermelon attaches there should be one or two tendrils. When those tendrils turn brown and dry up, the melon is ripe.
Carefully pick the melon up and look at the spot where it was laying on the ground. on an unripe melon the spot will be white or green. On a ripe melon the spot will be cream colored or yellow.
I read that the Black Diamond watermelon in particular gets a darker green, turns dull, and has a rougher skin when it's ripe. I've never grown this variety so I can't say for sure.
I hope this helps.
I have cut the watermelons open. They are not ripe.
A few questions that might seem obvious.
1. Are the watermelon plants getting full sun all day?
2. Is there enough Phosphorus in the soil to help the watermelons ripen? (this may seem odd, but it the plants are getting too much Nitrogen and not enough Phosphorus the may flower, produce fruit, then put more energy into vegetative growth and not enough into fruit production and ripening.)
3. Are they getting enough water? The ground should stay moist but not saturated for best production.
It's hard to say what other reasons the watermelon might have for not ripening.