Winter Squash Rot

Question

Why do most of my winter squash rot just after the flowers die?

Answer 1

It sounds like a pollination problem, though it could also be attributed to blossom end rot. These articles will help:
https://www.gardeningknowhow.com/garden-how-to/beneficial/insect-pollination-process.htm
https://www.gardeningknowhow.com/edible/vegetables/squash/squash-fruit-falling-off-the-plant.htm
https://www.gardeningknowhow.com/edible/vegetables/squash/pollinate-squash-by-hand.htm

If they have blossom end rot. This article will help:
https://www.gardeningknowhow.com/edible/vegetables/squash/squash-blossom-end-rot-causes-and-treatment.htm