Can I graft conifers in my unheated garage using a heating mat? I have not used a heat mat before, but I would guess that it would get the soil temp up to 60 or 70 degrees but the air temp is closer to 30 degrees. If I use this to heat the rootstock before grafting and then for the aftercare of the graft, will it still work?

I'm trying to decide if it's worth the attempt in my garage, or if I it would go better in my basement, which will probably range 45-65 night to day over the winter.