Since no one else has responded yet: My gut feeling is that all of these will fare better through the winter outdoors than indoors. Prep the soil (don't skimp - do it right) and get them into the ground as soon as possible, water in, then cover with 2-3" of organic mulch to stabilize the soil temperature. The ground temp changes more slowly than the air temp, so they may have a chance to get some root growth this season, whereas they might get off to a slower start in the cool soil of spring.

Where are they coming from? If coming from a nursery in, say North or South Carolina, they're in for a bit of a surprise. If they haven't been hardened off, I'd protect with a frost cloth at night, or even a sheet or tarp, until they get acclimated. On the up side, the leaves have probably already completed their task for this season (with possible exception of the hellebore), so if lost will not cause undue stress to the plant - it's the roots/crowns you want to preserve. Hellebores are supposed to resent being moved, but in my experience they've taken it well, even when moved at the wrong time of year due to a plant rescue situation.

Good choices, all. I just love the hellebores and epimediums in my garden.

Sometimes the most wonderful surprises come from rash decisions. Best of luck and please let us know how it goes!

This post was edited by agardenstateof_mind on Fri, Oct 25, 13 at 23:18

Thank you so much! Followed your advice, got them in the ground with generous mulch. They came from 40 degree weather in Virginia so luckily not much of a change. The hellebore, though...they suggested I either cut it back, or apply an anti-transpirant and make sure I water as needed over the winter. Cutting it back seems more full proof for a newbie like me.

These are my first hellebore, trillium and epimedium. I'm very excited!

agardenstateof_mind, as requested here's my update: every one of the above plants survived a very harsh winter to greet me in the spring. I think the mulch, as well as our nearly constant snow cover made a big difference. Thank you!

This post was edited by agathafroo on Wed, May 21, 14 at 22:49