Was that area under water this past winter or spring? If it was at any point, did the water freeze into an ice sheet for a period? IME Lamium needs dry conditions. The soil looks wet in your pictures... A couple of years ago I had a groundcover (not Lamium...) in a normally dry area get covered in standing water in late winter. The water froze into an ice sheet that stayed there for a couple of weeks. The groundcover died completely - like in your pictures.... Several years later it still is working on covering its old territory! It also looks like some of the Lamium has reverted to its ‘wild’ form, which can be very vigorous and is best to removed now before it takes over!

I thought I'd give an update on my battle with the Archangel. It's been almost a year since I first wrote this post. After repeated spraying with Round-up last year, the archangel finally died. I have been vigilante these last 11 months about keeping an eye out for new growth, but have seen no sign of it...until last week. I spotted a small but healthy patch growing in the same area. Once again, I sprayed (drenched it really) it with Round-up. It's been seven days and I just came in from checking on the plants. If anything, they look healthier and heartier than ever. Off to mix up another batch of RU and to pull what I can. These plants are hard to reach as they are growing right at the edge of the ravine underneath blackberry canes. I feel like I'm fighting what is eventually going to be a losing battle, but I will keep it up in the hopes of turning the tide.

I think you can transplant it at any time of year. Use a sharp hoe and then drag the transplants to the compost pile. Better yet, do it on a brutally hot day and let the cut off plants bake for a few days so they die before you compost. You'll need to do this for at least the next three years before it's all been transplanted, it will resprout from any root bits left behind. Seriously I'd reconsider moving it to new areas, wait and see if you still like it where it's at in three years. But if you do move some now, cut the tops down to about three inches before moving, the roots will quickly resprout, ready to invade new territory.

There were two acres of mountain covered in yellow archangel lamium, Lamium galeobdolon when I arrived here. It is largely evergreen even in my zone 6 winter. Most everything else growing in it are herbaceous perennials and bulbs that disappear in the winter. I do spray the lamium in the winter on short stretches of dry sunny above 40 degree days when all the other plants are gone and have had very good success knocking it back. It doesn't die until the spring which is a bit odd, but it does die. There is a seed bank of it in the soil and I don't have enough time to always pull the remnants so it can and does come back which makes for more winter spraying some years if I can get to it and the weather cooperates. The change has been huge and I have reduced the population and smothering of the mountain by 90%. One day I may get it out of the garden parts, but it has wandered into the next county and into the forest in places that are not high priority.