I have run pruned back mothers in a garage in our cold winters in Oregon with T-8 bulb lights right over the plants under a workbench with plastic in front. T-8 5k bulbs are cool enough for leaves to touch and not burn, but keep the plants warm enough in a cool place. T-8s are way cheaper than T-5s which get hot and will burn a too close leaf. I run the lights 20/4 on a timer. You have to also run a fan on them though, or you will get stem rot from water drops/condensation, bugs, PM/etc. You can also do this in a small space indoors like a bathtub or closet. Old mothers can get tough stems and stem rot though. Thse are really not perennial plants. I have found it far easier to clone them though winter.
To do that I clone them late season and ditch the mothers. After harvest I re-veg the mothers under 400w MH lights indoor and I take cuttings after they shoot about 8 inches (typically in November). I put the cuttings into a home made bubble cloner on a heated seed mat set at 77 deg. F. This will keep the clones warm. I then set a CFL Floro bulb on top of the cloner. They take about 7-10 days to start rooting, and 2-3 weeks to set good enough roots to plant. I them pop the rooted clones into 2x2 soil pots this time of year, and set them on the heated seed mat under the T-8 5k bulbs. I cover the bench with plastic in the garage to keep them warm, or in a corner someplace out of the way inside the house. They do not take up much room. Come late winter, they are large enough to pot up and size up under 400w MH bulbs or set outside in the greenhouses if it is warm enough.
Another option is really really old world. Breed and seed 'em IBL. No overwintering required that way at all. Genetics preserved. Though you will get some variation. Simply seed them out and harvest the seeds from the buds in the fall, and germinate them in late winter. No space required, no lights or fans required, no cloning required.