North Dakota (Zone 4a)
|I have considered doing that as well with my hibiscus. What lights do you use if I may ask?
Name: Chuck Pfeiffer
McKinney, TX (DFW) (Zone 8a)
|Definitely cut way back on the watering as suggested, be it mandevilla, hibiscus or bougainvilla. I place mine in the garage to overwinter, keep the pots on the dry side to avoid root rot, and force or let them go dormant, losing all their leaves. Early January, trim or shape them for new spring bud growth. I move them out for periods between freezes, sun light exposure and a good drenching. After frost danger, pull em out of pots, knocking the old dirt off the ball and roots. Then repot with fresh soil and lots of composted fall leaf mulch. Usually mix in some organic fert with new soil, but otherwise don't fertilize until after it warms up and active new spring growth emerges.
My experience is they come back stronger and better after the dormancy, as if they've been recharged than keeping alive and green in the winter. Hibiscus especially like to be root bound, and flower growth is delayed if the pot is up-sized. I usually reuse the same pot, only up-sizing the pot when top growth exceeds pot capacity.