Are there any areas in the United States that have a lot of short days (as in, few hours of sunlight) in the frost-free season and fairly to very cool temperatures during the frost-free season?
I've observed that Shark Fin Melon grows very well in such conditions—better than when it's even moderately warm and sunny. In fact, mine wouldn't even flower until it pretty much got cold and rainy, almost ready to frost. However, it grew fast during that time (not during the heat, but before and after the heat) and it set fruit, which grew pretty quickly. Notwithstanding it likes cold, it's not frost-tolerant (although the roots may survive down to a certain temperature and grow back; I'm not sure how cold they'll survive).
I'm looking for a region to experiment with that might inspire Shark Fin Melon to flower and fruit early on.
I imagine it would work well in cool greenhouses, after the season, though.
EDIT: If you can find an area that's hot for a very short while and then cold for a long while (before the frost), that may work even better, since it might be the change in the daylight hours that encourages flowering (rather than just the daylight hours).