Tony, I think they will perish if planted in open garden beds. Last year lost the only two bulbs I had of Hippeastrum evansiae which were housed in a roofed shade house during winter in zone 10. The winter wasnt particularly cold (zone 10 - warm temperate conditions) with a minimum in winter of 2 degrees centigrade. I have also grown seedlings of evansii primary hybrids to flowering stage in garden beds - but noticed that they also remain susceptible to colder winter spells (-3 degrees), and most have perished since flowering. Cheers Jim Lykos Lower Blue Mountains Sydney Australia