Checking your area and I would say Calgary is pretty cold.
Once it begins to spread here,it is impossible to pull out.
I have discovered this with Lamium maculatem.Its just horrible.
I have other Lamiums that behave themselves.Check Bluestone Perennials.
I have Golden Anniversery and White Nancy.They seem to be slower to expand.The maculatem has a silver chevron on a green leaf and purple flowers.
http://www.bluestoneperennials...
