MaryJane: Welcome to the Amaryllis forum. As you have discovered, Amaryllis will grow much further north than you would expect from the zone maps. To put it in perspective, some of the native Amaryllis come from high elevations which are colder in the winter. Some of the older cultivars like Red Lion, Apple blossom, H. striatum and H. johnsonii , seem to be more cold hardy. It seems to be dependent on the particular microclimate, more than the zone, where you have planted your bulbs. As long as the basal plate doesn't freeze solid they can do OK, esp. if the bulbs have a layer of insulating mulch over them, when a hard frost is expected. Wet ground is as much a limiting factor as cold, since the bulbs want to be dry during their dormant period. Wet cold bulbs will be susceptible to disease. Winters are usually wetter as you go further north.
