I bought a tomato plant from Lowe's about 3 weeks ago, I planted it in a huge container where it has grown quite a bit. I'm not sure if the heat is getting to my head today or really what I was thinking but I for whatever reason decided to plant it in the ground with the other tomato plants because I had one section in the garden left to plant something. I pulled the tomato plant up and realized how huge the root system is. It's already taken over half the HUGE 20 gallon pot. The plant is only a little over a foot in height. I decided to abort mission. I buried it back in the pot, watered and replaced the cage. Did I just kill this plant? What even was I thinking. Tia

Tia. Probably not if you didn't disturb or damage the roots too much. If it's in full, hot sun, try shading it for a couple of days during the middle of the day so it can re-establish its fine feeder roots; shade cloth or something lightweight like row cover draped over the cage is good. Give it regular water but don't let it get soggy. Based on your description it should be fine.

I've found that tomato plants are *very* resilient. Even with damaged roots they are good about sending out new roots. They are one of the easier plants to root. It would surprise me if you did any long-lasting damage to it. Those rootball get pretty extensive, eh? That's a good thing!