If flowers are removed as soon as over hellebores will flower again spasmodically. Last year I had 2 good,shows. I remove flowered stems ASAP to prevent seeding amongst my clumps.
I know it's a slightly different world down here.....not as cold,in winter....but my hellebores are enjoying the conditions.
I think young plants are just as hardy as the mature ones ...it's probably,that their roots haven't yet gone deep enough to,cope on their own. Shouldn't really need to water hellebores in the ground at the moment.
Nut, you may be right about some plants coping better than others. Lots of breeding may create stronger/weaker varieties but, down here I havent really,noticed that