I have had 3 luffa plants. I transplanted them outdoors into the ground in April. They did not flower until early September. When I had my first few luffa fruits a few weeks ago, they were silky and tender. Then, gradually, they have gotten tougher even when they were not big in size. I am trying to figure why they get tough disregard their sizes. could it be:

1. the cooler the weather gets, the tougher they get? or

2. tender fruits were produced by a different plant/plants. Now, I only have one left. This is the most healthy one. Its stem is big and strong, whereas the other two were tiny. The tiny stem ones are gone already. Since all of the 3 plants are all intertwined, I couldn't figure which luffa fruits produced by which plant. Is it possible that the tender fruits were produced by the less healthy luffas? were they flowering earlier than the healthy one and produced fruits earlier too. Thus, now, all I get are the tough fruits produced by the healthy luffa?

Thanks