This is the second time I've tried growing luffa sponge gourds. The first
time was nearly 20 years ago, and all I can remember is that it frosted
before the tiny gourds got big enough. This time, I planted them very
early. However, even though the plants have vined up all over my trellis,
there has not been even a single flower on them.

Anyone have any ideas for why this might be? The plants are healthy and
growing.