I find volunteer tomatoes are the hardiest tomatoes that I've ever had. If you want to know just exactly what you have, try winter-sowing-and why not just where you want them.

Thanks for your answer.

I agree. Volunteer tomates have been hardened off naturally and know when the right time is to come up.

I do think you should label though. Take a rotton tomato that if freshly fallen and put it somewhere specific. Stick a plant label in the ground and label the variety. If you only have one hybrid, then I assume the rest are heirlooms. In which case, that's even more reason to label. If you don't, that's how varieties become extinct.

If you really, really want healthy tomato plants, grafted tomatoes are amazing. There are three plants in the master gardener demonstration vegetable garden that are totally healthy, and MONSTEROUSLY HUGE.

What did they use for the rootstock and what did they graft on to it?