the shorten daylight is what triggers dormancy along with temperatures. Just let it do its thing.

Mike

I also believe the amount of sunlight is the primary trigger.

Sage, they are genetically programmed to rest during the darkest months, even in the warm tropics. I think it improves their overall health and blooming to go dormant. Those who grow them farther north need to shorten that dormancy period somewhat but in SoCal you should be fine.

A couple of winters ago I tried keeping a few young plants going under grow lights inside and some still went completely dormant anyway, and all dropped some leaves.

However, if you get a surprise freeze, those Christmas lights will come in handy!

I'm not sure that they go completely dormant in the tropics, such as in Hawaii, so it may not be strictly necessary for this to occur, though it is fine if it does.

As a side note, my observations indicate that temperatures as well as day length determine many trees' entrance into (and exit from) dormancy. Here in Florida, if we have a warm November-January some of the deciduous trees will keep most of their leaves (just dropping a few) while others will very slowly shed leaves during this period without much, if any fall color. However, if we have an extended period of (or back-to-back) cold spells during the November-January period, the deciduous trees rapidly turn the usual fall colors and then drop most or all of the leaves. I have observed this many times.

I know my trees even under my 600 watt HPS light will drop there leaves. My 'Leela' is blooming entirely leafless right now. Off the top of my head I know my 2ft tall 'Bill Moragne' is also under that light with no leaves. They are getting on average about 12 hours of light and 12 hours of darkness and most of them will stay leafless until they can go outdoors in the spring.

Andrew

on Hawaii five-O last night in the background there were 2 plumeria, one covered in leaves and flowers the other appeared dormant. I do not remember them going dormant when I lived in HI. I know they didn't bloom as much during the shorter days of winter.

Christmas lights of today are much, much cooler than those of our youth. Most of them do not emit enough heat to be of any benefit. Those big old christmas lights usually will produce more heat but even those are now engineered for less heat/less energy/less fires. Look for heat strips that are designed to wrap around exterior pipes. They do not emit enough heat to burn the plants but will keep them above freezing. They are very popular here because none of our pipes are protected-mine run up the outside of the house.
Tally HO!