Khasiana, sp. Viking, some SE Asian mirabilis forms, and rowaniae all have a "dormant" period in situ, though it's not necessary in cultivation. Like I said, it's not really a dormant period in the true sense where they save up energy blah blah blah. Because of the monsoon cycle, there is a period where they get very, very little water, and more or less stop doing anything until the wet season comes back. I don't know anything about sp. Cambodia so I can't comment, but I would venture to guess it would react the same.