Good question. I have hesitated asking a similar question (trying to figure it out on my own)

Plus, the cheapo plastic pots I have my plants in (bought at Wamart for $1.89 each) are not rated in gallons, but size.

I went from 4 oz clear plastic cocktail cups to 16 oz SOLO cups, to 6" plastic pots and now I have them all in 8" plastic pots. No idea how many gallons they are....maybe 2 or 3 gallon.

I would think the milder peppers should go in the larger pots, like the Jalapeno, Peppadew, Mini Bell.

The bigger the better, 5 gal at least. 2-3 gallon pots some use with good results. I planted Peppadew last season and had ripe peppers in the same season. The peppadew can get quite large especially if planted in ground, I would put that one in a large pot. Also which ever pepper you want/favor, plant in the bigger pot. As for me I plant all my super hots in larger containers and milder ones in smaller if I run out of larger pots.

Mark

You have the right size containers, the one you would like to grow bigger use the larger container. If you think about the minimum size container the answer will be very complicated. I have grown Ghost Brown in 7 gl and 1000g Greek Yoghurt container it is getting flowers:

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Good luck
Caelian

So, you just now have seeds? Not seedlings / plants? I'd say that's pushing it time-wise in zone 5. Not saying you won't get anything, but, it's going to be pretty late in the season.

If you want to keep any over the winter to have a head start next year, I'd recommend getting smaller pots when the time comes (pick them up on sale at the end of the season). I would go with 1 gal max.

I haven't grown any of the specific varieties you have, so can't really recommend which for which container.

Tsheets gives me an idea, if it is going to be late according to your zone then use small container, it can speed up to yield fruits. I am not an expert, just share my experiences.

Caelian