On Nov 30, 2012, at 4:11 PM, Barna Sipos wrote: The following species are reliably hardy in a continental climate (Warm summers, cold winters) into Zone 5. I have grown these trouble free for decades in Kansas City MO, USA.. L caldwellii L chinensis L longituba L sanguinea L sprengeri and L. squamigera and L. incarnata The next 3 species are slightly more tender and require some protection in Zone 6, but should do fine in Zone 7. In my cooler zone they survive, but do not bloom reliably every year due to winter foliage damage. L haywardii L houdysellii L radiata I am not completely familiar with the next 3, but they should do well in USDA Zone 7, 8, 9 L albiflora L rosaea L traubii L aurea is the most tender species of the lot and will not bloom reliable with repeated freezing temperatures. It is also not widely grown under the correct name. You should be aware that any species that produce foliage in fall in cold climates will have freeze damage which can weaken the bulb, prevent flowering and over the long term kill the entire thing. Alternately those species that produce their foliage in spring and do not get severe cold and freezing damage are much hardier species. And as a rule, those species with more succulent foliage are most susceptible to freeze damage. All species benefit from warm to hot summers and all dislike extreme baking conditions in summer. Best Jim W.