I was planting a "free July" tomato plant, but when I was trying to pull it off the plant wall while planting, and accidently broke it off, what do I need to do to help it survive? I was planting it about an inch off the bottom of the pot so that it could grow roots all over the stem, in order to promote root growth as much as I was able to.
The specific type of tomato if that matters was a purple cherokee.
You can root the part that broke off in soil. The problem is, you'll probably want to shade it for a few days, or the sun might kill it. Just plant the cutting in the soil, water it, and shade it. After a few days, if it's still alive, it should be fine.
I've done this successfully before for at least one tomato plant that a cutworm or something like one severed, granted I didn't need to shade it since the area was already partially shaded. The plant was severed more than once; so, I did it multiple times. The knowledge of sun killing new cuttings (and some transplants) comes from experience and observations with cuttings and transplants.
Humidity domes can help outdoor cuttings, if it's not too hot (think less than 80° F.) but it's not really necessary for tomatoes here.
Giving the plant a little extra potassium (e.g. potassium sulfate) should help the plant, too (to absorb water and other stuff), but again, it's not strictly necessary.
As for the other part of the broken plant (the stem that already has roots) in the soil, it may or may not grow again. If it's only at the soil level, it will likely die. If you could put that indoors very close to a 22+ watt fluorescent bulb, it might grow new shoots, but it really depends. The more and closer the light, the better. If there are sections of stem where leaves are or were, that will help. If it has leaves, it has a greater chance of survival, unless, maybe, it's pretty young.
