It's news to me that any rain lily (zephyranthes and habranthus) would be hardy in the ground as far north as you are. I think if I were you, I would divide the clumps you have and let them multiply in your yard. It sounds like you have an exception to the rule (or a different plant with the same common name). Crinums will bloom in response to rain, but they're no hardier than rain lilies.

It might be too that you do have rain lilies, but that they are planted in a micro climate of sorts on your property.

I have a patio dahlia that has returned for about 5 years now, that 'should not' be hardy here in my zone.

I think you can maybe identify a warm microclimate area of your property as being any area where the snow would melt off earliest in the winter. Areas where it lingers longer than others areas, I would think might be colder than normal on your property.

I'm going to try and extend the daffodil season here by paying particular attention to where I plant them. I want to plant some where the snow first melts off, and where if melts off normally, as well as the areas where it seems to linger the longest.

Sue

I am in 5a also and have many Rain Lily bulbs that have survived the winter.

It is good to hear Rain Lily-Copper Lily bulbs are hardy that far North. It could be possible they have hardened out for your climate. Looks like you have a winner there and need to divide as often as possible, your neighbors just may love you. The best we are able to do it try.