auto not flowering

3 plants, all autos.
Started dec 20. 2 are budding up good.
One is huge but not switching. Hydro. Lights 24-7

I would goto 12-12 but... theyre in cold garage and the lights are what keep them warm/alive.
hate to run a heater...

Is there any other way to force the switch?

They are too smelly to bring indoors.
Buds on the flowering plants are nickel sized so I think I waited long enough.
Hate to kill a good plant...

Lingus

What the light type you're using. I have one in a crawl space... it's cool in there as well at this time of year, but a space heater is expensive to use. You may have to switch 12/12 and see how cold it gets when lights are out. Or you could lessen to 18/6 and see if that helps. That's what my light cycle is.

Mh light 400watts.
I have a thermometer to watch the temp. Wonder how long it'll take her to switch.
Once she gets flowering I should be able to go back to 24/7 maybe?

I'm used to growing indoors and fighting the heat..
Then I moved.

Thanks

I run my autos 18/6. you might try 20/4 for a few days and see what happens and with only 4 h.r off it shouldnt get too cold

I have mine on 18/6 as well. I have had others that I switched to 12/12 and they took off. Then I did switch them back to 18/6. Some say this stresses the plant out however. I didn't notice any issues of stress going back to 18/6. These plants took forever. I figured I'd try them thinking I could have plants in flower in my veg area, but each time i have had to push them along.