It is no more invasive than many other groundcovers and a lot less of a problem than many other more aggressively spreading plants. In zone 5, overwintering is even iffy unless well mulched, so I doubt you should be faced with much of a problem. And while it would appreciate some midday sun protection in hot climates, Ceratostigma is not really a shade lover so how well it might spread in a very shady planting area is up for discussion. I have never found it a problem to remove where it was not wanted.

Don't really know about Zone 5, but here in 7 it is certainly NOT invasive. As a matter of fact, it is a rather slow increasing plant, and I have been waiting 3 years for it to make a real show, which it has yet to do. I keep waiting.

George

Thanks so much for responding so quickly gardengal & geoforce! I'm getting a mite discouraged about this seemingly wonderful groundcover. It just looked so colorful in the fall pictures on the web with its blue flowers and chartreuse/red leaves! We are talking about the same plant--ceratostigma plumbaginoides, yes? I saw yesterday that pictures of just leadwort & likewise for just plumbago (minus its latin name) didn't look quite the same. Are they all the same family?

At the very least I'll try one plant & see how it goes next spring. No harm in doing that! It is quite shady back there in my back of the lot, although it's all pretty much dappled shade/shade.

Ceratostigma plumbaginoides less likely will develop burgundy/red color in a shade. I had it for several years in such conditions and while it was blooming it never did anything in a terms of foliage and didn't spread too much.
As soon as it was moved to sun/ part-sun location it really took off and right now I have a fantastic display of flowers and a foliage.

OK, that's it. Too bad it's not going to happen but at least I have a whole winter to decide what IS going into this shade garden. Thanks, all!

I'd consider Gaultheria procumbens, wintergreen, for a good shade groundcover. Evergreen, spreads nicely but manageably, produces small, pinky-white flowers followed by large, bright red, edible berries and the foliage will take on colors similar to that of the leadwort in late fall or with cold weather.

Here is a link that might be useful: