Tomatoes are weeds, peppers are, zucchine certainly, butternut also and … grapes too!
Yes you see if seeds remain on fertile ground they will pop up next year. We already had quite a lot of rogue tomatoes and butternut squashes.
In Umbria you will be able to spot the odd lonely grapevine here and there. Most of them are remains of an abandoned vineyard which got ploughed over. Bit of a shame especially since lots of these vineyards were very small, they weren’t as neat as the the ones you see in modern days and the grapes would be climbing up the trees.
Anyway, to mark out a piece where I had sown some lettuce I stuck a ‘dead’ piece of grapevine in the earth. Wait a few months et voila, a new vine is born.