In theory - 2 in each. But they will do better, be less stressed, produce more, and require less work on your part if you just do one indeterminate in each.

Some will claim 3 but that would just be asking for problems IMO and a great deal more work on your part to keep them healthy, fed, and watered properly.

But that also depends to a degree on where you live, your climate, etc. and you don't indicate that info.

Dave

I live in southern ca about 5 miles from the beach. Maybe i'll try 1 and 2 and. See how it goes.

Besides how much soil each plant needs, something else to consider is how much space you'll have for the vines, whether you'll prune, and how the vines will be supported.

I don't grow in containers, but one issue that comes up in discussions is how the color of the container affects how the sun heats the soil. Some people wrap their plastic containers in white plastic or mylar to keep the plants' roots cooler.

TB, for years I've grown tomatoes in half-whiskey (I know from the neat smell) barrels, right up against the brick knee-wall of my south-facing attached greenhouse. One plant per barrel, they grow extremely well, partly because of the reflected heat from the brick in full sun. I usually remove some of the old soil, replenishing with homemade compost. After plants in and soil sufficiently warmed, I put a few layers of newspaper on the surface, leaving space for the stems, of course, then cover that with a layer of straw. Being in containers, they get some fertilizing every couple of weeks, mostly with fish-kelp emulsion from Neptune's Garden. I put a large steel stake in the outer two of the seven barrels and one smaller t-stake in each, using a modified Florida Weave to hold things together. Good way to grow tomatoes, in my experience. Good luck. Gary

I have grown two indeterminate tomatoes in a half whiskey barrel successfully. The first year I did it, I added only one drainage hole in the bottom. It was an unusually dry year, and water drained out between the staves, so everything went well. But in the second year, we had rain for a month before I planted out and the wood swelled so much, no water came out through the staves. The drainage hole in the bottom swelled and got plugged up with mud. Although I drilled a couple half inch holes in the sides near the bottom, the soil stayed wet through most of the summer. I was watering my other container vegetables every two or three days in July, but almost never had to water the barrel. Be sure to use a potting mix that drains well and make lots of drainage holes.

30 gallon is a good size for container tomatoes. One per barrel would be plenty. Be sure the barrel has good drainage.

Here is a link that might be useful: How to choose containers for growing tomatoes