I believe Craig (nctomatoman) grew his dwarf tomatoes in 5 gallon grow bags last year. Here is a link to the video of the ones in his driveway so that you can judge for yourself his success.
http://www.youtube.com/watch?v=HShW6...ayer_embedded#! Keep in mind that while these plants are certainly shorter than many indeterminates, some are over four feet high, so they're not tiny things.
They looked very healthy to me, and I'm planning to get 5 gallon root pots for about half of my tomatoes. I will also get some 7 gallon root pots for my larger-mid to smaller-large varieties. (If that makes sense)
The only two I will put in larger containers (probably 10 gal.) are Amish Paste and German Johnson, as those two grew very large for me. One of my Amish Paste last year grew over eight feet tall in about 6 gallons of soil. While it did okay, (and produced more fruit than many of my others) there was too much concentrated root ball to keep it watered evenly, especially in the heat of the summer. So I know that one could benefit from more space.
I would like to hear from other, more experienced, gardeners, but it seems to me like you could get much smaller containers (but still quite comfy for your plants roots) get a really nice soil mixture and still save a lot of money.
