I have an enclosed deck, with two heaters, a humidifier and fluroescents. My trees do slow down from time to time. However, each tree has its own resting time, but with temperatures above 85 degrees, the 40 some trees keep me busy all winter!
I have to admit that I do feed my trees (weekdays) with 1/4 teaspoon of superbloom 12-55-6 to a gallon of water in the last watering. (if they need watering)!!!
On weekends I water them with clear water!