I would think that as long as the plants aren't tall enough to be unmanigable, you would be OK repotting. When you re-pot, be sure to bury the stem all the way to the first set of leaves on the stem (It will grow new roots along the portion of the stem you plant)But I'm far from an expert at this - this is my first year, and everything I know, I've learned from reading here!

The tomato forum would be a good place to search to see if the question has already been answered, and if not, ask away :) there are some really helpful and knowlageable people over there!

i realized too late, that my pots werent big enough--i repotted a heirloom tomato that was almost 4 foot tall- i just dug a deep hole--in the ground, and buried it deep, watered it well, it didnt even know it had been moved!

They will be absolutely fine!! I just potted some leftover tomato seedlings I discovered I had still in tiny cellpacks. They were all about a foot tall with a few tufts of yellowish leaves at the top only. I buried them in good potting mix in large pots all the way up to those little tufts of leaves & a week later they've grown a good 6" already, are deep green & already branching out.

Tomatoes are VERY resilient.

whoa... I just had the same questions. I have a 18" tomato plant (first set of leaves about 8" up) in a 4" pot. Its definitely time to repot. Thanks for the motivation!

Kim