Jim, I can't answer your question the way you asked it, but I can tell you that Haemanthus multiflorus of horticulture has been known to survive a winter outside here against a wall. What "against a wall" means varies from year to year, but in a typical winter, plants underground and against a wall evidently do not experience freezing temperatures. They are also in the rain shadow of the house, so they are relatively dry. I've never known plants wintered outside to bloom, however. In my experience, just about anything which is winter dormant and does not have live foliage above ground can be wintered outside this way. Jim McKenney Montgomery County, Maryland, USA, USDA zone 7, except within five inches of a south-facing wall where it is (below ground at least) zone 9 or 10.