To grow watermelons I take a 1 cubit foot bag of mixed manure and a 1 cubit foot of cheap topsoil.from the garden store and mix them and then dump the mixture on top of the ground. I don’t even mix it in the soil. I then lay out cardboard about ten or twelve feet around the pile of soil to prevent weeds.
Doing this means I don’t really till down. In places I only have 1/2 an inch soil before I hit coral limestone.
It may be a soil issue but it may also be snails, slugs and beetles eating the shoots.
Interesting method. The vines do well at first, but then after the weather warms up a bit, the vines all of a sudden just collapse. This didn’t happen the first year. We only had a little blossom end rot.
After that first year, no success growing cukes, melons, squash.
Sprinkle Cheyenne pepper around the area. I use the pepper to keep slugs, and destroying bugs from my squash, mustard greens and corn. I sprinkle the area immediately around the plant, on the plant and even the corn silk. It keeps the bugs and slugs at bay.