Very good to know! If they are anything like wineberries, once they get going, you'll really have to keep on top of them. With wineberries, anywhere the stems touch the ground, they will root and form new plants, and the seeds are also lovingly dispersed by birds. Totally not trying to discourage you, just sharing my experience with wineberries (invasive in my state) in my yard =D I don't know if native blackberries behave this way as well, but these dang wineberries have left a bad taste in my mouth, pun intended ;-) !