The late great Claude Barr did quite a bit of playing around with species Calochortus (40 years ago?) on his ranch in South Dakota (zone 4b/5a). He concluded that nearly all (there are about 57) species were not hardy for him although he got many to limp along. If I remember right, he recommended to try only 2 or 3 in his zone with a good winter mulch. Most need really dry and warm summers,
