I have grown in as small as three gallons with good results .One plant per pot . Peppers cross breed easily ,so if you plan to save seed keep species separated .

I don't have Bell peppers, but my in-ground, 4 year old jalapeno is 4.5 feet high. They will grow big, so if you want them to stay small, then I say small pots, and I agree. One per pot.

I have a couple (grown from seed) Greek peperoncini plants, and after one year they are still about 6" tall in the ground. They do bear peppers!! Lots of peppers!

Suzi

I agree with the others: one plant per pot.

My friends generally grow in 2 - 3 gallon containers. This size is especially good
for the smaller, more ornamental peppers - like Thai chilis, for example. My brother
grew a Thai chili in a 5-gallon container last year, and it out-performed the peppers
in the smaller containers.

I grew a Japanese Red Pepper in a .71 gallon container last year -
it was given to me in August (by a friend who discovered the joy of peppers late in the season),
and I harvested some very bland pods at Christmas-time. It worked, but not well...
and the crop consisted of 17 pods, only half of which were edible.


Josh