I live a solid zone 9, Sarasota, FL. Our night temp goes above 70 for most of May through September. It was more the night temp that the University of Florida agricultural agents I've contacted said would keep tomatoes from setting crops. They recommend a two season year to maximize my yield. Start seeds in Jan for first season, then destroy the plants. Start the 2nd season in Aug. They explained that trying to keep the plants through the non-productive months just highly raised the propensity for developing disease and spreading it throughout my crop. It wasn't worth the trouble they encountered. Hope this helps. Olin wrote: > In our desert climate, the daytime highs regularly exceed 90 deg. F after > May 5. Any suggestions for extending the period for fruit set in hot > weather? -Olin