I foolishly set up for a lager batch this weekend without thinking about the fact that I already have a couple ales in the fermentation chamber. My garage is holding about 2°C, so I don't need to warm it too much above ambient, and I only need to worry about it for maybe 4-7 days before it can go in the chamber with the ales.
Once fermentation kicks in it should help with keeping the temps up, but I'm wondering if anyone has a proven solution for warming a fermenter without temperature control. Warm water bath? Chemical hot packs? Move it in and out of the fermentation chamber a hundred times a day?