Neal, believe it or not, I cleared that many in fall. When doing that I obviously brought new seeds to the surface which then sprouted. They stayed green all winter, and now they have big roots. Not easy to pull or to hoe and the warmer weather has caused them to get bigger and stronger. I brought some cardboard boxes home from work. Hopefully I'll get some cardboard down this weekend to smother them in at least some areas.
But, there's a problem with that too. I moved a lot of perennials last fall, and they were marked, but many of the markers disappeared over winter. They were either blown out of the soil, trampled by deer, or whatever. I've been hoping a few perennials would show themselves so I don't smother them, but I can't wait any longer.
I got so mad at the reseeding that I bought a jug of Preen. I have been trying to do all organics for about 5 or 6 years but now my soil seems too fertile. Any seed that gets near it sprouts! (I tried applying corn gluten last spring and fall with, obviously, no effect).
Karen