It hasn't been my experience that they prefer poor soil. But what you describe doesn't necessarily sound, to me, like poor soil. Where do you live and garden? I live and garden in Oklahoma, and the soil, though much better than some places I've been, is NOTHING compared to my native NJ (central part of the state). There, landfill soil is typically better than topsoil here!

For whatever the reason, volunteers tend to show more vigor than that which we plant where we want it. I'm not quite sure why. Though I suspect it has something to do with timing.

George
Tahlequah, OK

I'm in TN. Most of what we have here is red clay unless we have a load of stuff brought in. The little ants are tending it right now... there isn't any aphids so I guess there's sugar on the plant somewhere.