This is my first year with a vegetable garden and have read may threads in Dave's Garden. I have something I haven't read about - tomato plants setting off babies/volunteers. The first ones I saw were near the base of the tomato plant that grew 5 ft tall, but only produced about a dozen smallish (for beefsteak) tomatoes. I never let any fall to the ground to go fallow. Next I have a couple small plants started from seed in pots transplanted mid Oct that have a volunteer next to them and lastly a volunteer in the middle of the growing beets that were planted mid Oct too (and are 6 - 8 in high).
This is probably all a moot point since we may FINALLY get cool weather this week (mid to high 60's) and continue in the 40's at night. I guess it will be too cool for tomatoes.
You could be getting some scattered seeds from little critters sharing your crop with you. I've got volunteers coming up all over the yard from the fruit snatched by the ground squirrels last year. If they were in a half-way decent spot, I left them (but provided no special care); of those, some did well some didn't.
Well, we will see if anything comes of them, especially since tomatoes are not usually a winter crop. We can get a few nights with frost, but I don't think I've seen any days less than mid 50's. Two years ago we had a couple cold nights with some down to 26! DD took a frozen disks 1/2 thick from horses water barrels!
We get a lot of volunteer trees (not fruit) from some unidentified prolific local variety. Usually a dozen starts in the pasture during summer if we have had decent rain in winter. They are very fast growing and some have started literally next to the foundation (I guess where seed has blown). I need to cut and kill those - especially the one wedged between foundation, AC unit and gas line - as they would be fire hazards. We try to transplant the ones from pasture during their dormant winter period and place them where we can benefit from the shade in the house.
If your volunteer tomatoes are from hybrid varieties, they aren't likely to reproduce true to the mother plant. Hybrids are a cross of two or more varieties and seed from them will revert to one of the plants used in the hybridization process. Sometimes you will get good tomatoes from them but I've seen cases where they put out very undesirable tomatoes. It's just a dicey proposition. If they are heirloom varieties, they should reproduce true.
The first 2 plants were just from WalMart, then 3 from my seed packets in a different planter and 2 from neighbor's seed packets planted in pots & transplanted in Oct. I doubt any are heirloom. It will be interesting to watch, none the less.