Are you saying LED's or Flourescents flicker? I had experimented with some LED's in -20 freezer warehouse and most were instant on full brightness. We ran mostly 4ft T5s there. Not sure how much is due to bulb size, but in my experience T12s have trouble in lower temps. But that may also be cause they are more likely to have ancient magnetic ballasts in them. T8 with an electronic ballast should be good down to 20F or even lower. They may not come on at full brightness, but should have no problem firing.
