I am wintering 2 Juniper Bonsai in my unheated garage. One is a starter plant abut 5 inches high that cultivated as a sprig this summer. It is in a plastic pot and not yet in "bonsai" soils. The other is from a class I took with a bonsai master, Chase Rosade, this spring. It is in a bonsia pot in a good soil mix.
Both have been thriving both outdoors and in their first couple of months in the garage. Watering has been sparse as I have read, and a gro-lite provides the necessary hours of light they need. Last night however, I notice the soils were hard frozen. Should I still bury them in mulch or soil in the garage if they will be subject to only a few days of deep freeze? Usually the garage stays in the 30's unless we hit the low teens outside. I will be very upset if I've managed to damage them. I read about the three levels of freezing - the soil, intracellular and intercellular, and it doesn't seem as though my garage environment will subject them to the worst scenario. Thanks!