Mary, my guess would be from seeds... my jump-ups reseed very prolifically... but the young plants that are just coming up this time of year to seem to manage to overwinter, as well. I wish they were easier to collect seed from so I could plant them "on purpose" ! (I have managed to collect some seed, and it will grow for me, but those little pods break open and scatter their seeds generally before I get to them, for the most part.)
