I grow borage everywhere...or rather, it grows itself everywhere. Its very successful at self seeding
I don't know about its accumulator properties nor have I ever dug one up to check out its root but I can attest to its insectiary properties. Honey bees love it and hover flies hang around too.
It will come back when you chop it down (although Id recommend leaving a nurse branch intact). I cut ours back all the time to give to the chickens; very good fodder, they seem to like it. Just hack off a big stem and throw it in run; they'll eat every last piece of it, stem and all
