I have never moved one that old. When you do move it, can you take a picture of the root mass?

So you want disaster photos, eh? :) At least give me an idea of how far down to dig without cutting through the roots. Niobe has been in mostly shade, ever increasing shade, for 4-6 years now. So I doubt it has a full 12-year size root mass, whatever that should be.

Carol

When you decide to move it..hopefully it is still cool weather and keeping moist after its move is key to its adapting/success to its new planting hole..Other than early Spring...I "prefer" to move mine while they are dormant..generally for my zone is around late Jan/early Feb..Dig at least a 2ft diameter around from the base(where the stems are) and probably 3-4 foot deep..once you have started digging out the perimeter you'll see how truly far you must dig down to encompass all the roots..inspect and if you have any roots that were damaged by the dig..take your pruner and prune the torn roots smooth...have your new home dug and ready for the move...it you don't have problems with critters then generously dust the new planting hole with bonemeal...and never let that new home dry out..keep moist...Jeanne

I have gone to an old abandoned house in my area (early in the spring) and dug up a small part of a clematis growing under a tree. The tangled tree roots made digging nearly impossible, but I got a new shoot with some roots attached, and that was enough.

If you want to be really safe about it, you can root some of your Niobe vines this year and move the rest of the plant next spring.

Just run a clematis vine through a pot of dirt, weight the dirt in the pot down with a rock or something (so the squirrels don't dig it up), and water it now and then. By next spring the vine should be rooted just fine, so if something goes wrong with digging the momma plant at least it's not a total loss.

I've moved a few clematis in spring and in late late fall with success. The old Montana Reubens, I dug a massive rootball to lift it, but had to finger out the roots in order to fit it into a MUCH tinier hole between the roots of an established tree. I thought I had killed it, but its alive and growing this spring. Bone meal, rose food, whatever...I just think they are hardier than they look.