Thanks for the several comments. It does sound counter intuitive, but if the problem is keeping a pot cool enough. Where a large (and efficient) cooler is available, then heating a small volume box in that cooler is indeed more efficient than plugging in a refrigerator to hold at a slightly higher temperature. Richard and I both live in the PNW, and keeping plants, or seeds, consistently at 45 or 50 F during winter is problematic due to temperature fluctuations outside. Kathleen PNW Coast, WHZ 8, dryish cool summers & mild wet winters; tonight, it's a mix of hail and rain