I would disagree 15 gallons is a minimum, and you will get get ton's more
peppers, or tomatoes in larger pots. I grew Sungold in a 30 gallon pot and
harvested over 800 tomatoes.

I grow about 18 varieties of peppers, an 18 of tomato every year.

Do what you are doing, you got it right!

I grow in all size pots too. I have a bunch of 5 gallon pots I use too, but
no doubt the plants are smaller and less productive. In 15 gallon I get about
the same yield as in ground (slightly less), I grow 4 pepper and 4 tomato plants
in ground every year.

I have been growing plants for over 40 years.

My 4 foot t5 fixture is a VHO type, not the common HO type, one of 4 light
fixtures I have. I grow raspberries, strawberries, peaches, cherries sweet and
sour, blackberries, blueberries, currants, onions, melons, watermelons, pluots,
plums, elderberries, honeyberries, beans, lettuce, radishes, oregano, basil
(numerous types), thyme, sage, chives, cumin, black pepper, ground cherries,
cucumbers, and many flowers and ornamental bushes and trees.

You will find radically differing opinions on sizes of pots. My 6 gallon work but there is a difference between them and my 18 gallon tubs.

It sure sounds like you discovered the sweet spot with your container garden. I'd have no idea where I'd find 15 or 30 gallon pots at a reasonable price.

Please tell me more about your 15 and 30 gallon containers. Can you provide photos of the containers? Where do you find them and how much do they cost? Even a 15 Gallon container is at the absolute upper weight limit of something that could be moved. Do you just set them out somewhere and leave them there or dig out a home for them and set them into the ground. I'm intrigued and would love to learn more.

I've been gardening about as long as you have. It sounds like my garden is much smaller than yours. I have 4 raised beds used primarily for squash, a somewhat small area for cantaloupe and watermelons and beyond that I have room for about seventy 5 gallon buckets and that's it.

I'm in north central Alabama and the soil here is pure rocky clay. Virtually impossible to grow anything in ground here so I moved to containers out of necessity when I transferred up here 30 years ago and don't think I'd ever go back - much less work, no weeding and easier to maintain. The only downside to 5 gallon buckets is the need to water every day regardless of whether or rained or not.

I've never gotten 800 tomatoes from a single plant but I do get hundreds of tomatoes every year - probably around 800 to a 1,000 from my 30 plants (not counting Romas or Cherry tomatoes). I also throw out several dozen each year. I grow several heirloom varieties that are not noted for being highly productive but are meaty and taste incredible. Basic tomatoes like Better Boys generally run between 14oz and 18oz and produce 60 - 90 tomatoes per plant over the entire growing season.

Bell peppers do exceptionally well in my 5 gallon buckets and my green bells grow huge - they're the only veggie I don't grow from seed - I buy 2 trays of Bonnie Green Bell - six tiny starter plants about 3 weeks old for $1.50 each. They must be genetically engineered and the seed will not germinate but my $3 investment yields at least 250 huge, stuffing sized delicious sweet peppers. We also freeze 7 or 8 (or more) gallons of them each year - I cut them into 1/2" strips, lay them out on a large cookie sheet and flash freeze them in a chest freezer before putting them into gallon Ziploc freezer bags and vacuum packing them.

Can you tell me how to attach pictures to a post or reply?

#15 pots are not 15 gallon. They are 13 and a fraction gallon. Even my 6 gallon don't do badly. I got mine used at a local nursery for $3 ea. Attaching pics here is easy. Notice on the lower header there is an item marked "photo". Click that, then select a pic from your computer.

I imagine fabric pots could be useful in Alabama. Plus they pack flat when not in use.
Fabric pots

The rigid pots stack well once they have been cleaned.

I wanted to mention since we are talking about pot size is that their is
nothing wrong with using smaller pots, yield may be less, but you can grow more
varieties that way. I often just want to try some fruits to see if I like them.
You can even grow trees in 5 gallon pots. I just prefer not to for the most
part, but it certainly can be done successfully.

I'm incorrect in my first post, in that it is too small, to each his own, if
it works well for you go for it.

I have my own reasons for using the size I do. I want greater yield, I want
to water less, I want to minimize the stress to the plant. (the stress can be
managed well though) We each have different goals and smaller pot sizes may work
for you. You know many dwarf tomatoes grow to full potential in 5 gallon posts.
Anyway I wanted to elaborate more. As 15 gallon and 5 gallon have their place,
depends on your expectations, needs, and skill.