Hey Alex...Good question! Watermelons are more susceptible to frost damage than they are to heat damage, so I would say that almost any watermelon would be fine for the tropics if temperature was the only factor you are worried about. Having said that, I would also insist on trying to grow a cultivar of watermelon that is disease resistant. Especially if they are resistant to anthracnose and fusarium wilts. There are quite a few varieties out there that are resistant to those two fungi. I would recommend 'Jubilee II Hybrid', 'Crimson Sweet' or 'Ruby Hybrid'. I hope this is helpful to you. Let me know if you have any further questions. --Robby
