How big of a container do you need for a tomatoe plant to keep on the patio? They would be medium size tomatoes. Thank you!

No one has answered you yet, so I will give my own personal experience. I have planted in 5 gallons and done fine. I am also trying that upside down planter which is only about a gallon and says that you can have tons of tomatoes. Usually I do try to put them in a larger container or the ground. I did great last year in a half water barrel, with a Roma and a Beef Steak in the same container.
I hope some one with more experience answers so I can get some good tips.
Good luck.