Either buy a pre-made mix or create your own with peat, bark fines, perlite and a little compost. Research the 5-1-1 mix in the Container forum if you're feeling ambitious.

Thank you oxboy :+) I'm going to get some mushroom compost to mix with my cheap potting soil. Have any of you planted directly in composted manure and compost?

I am sure there is a good country song here...
"Love those sweet Texas tomatoes....but they keep breakin' my heart!"

You don't want to plant in straight compost or composted manure. These are too rich, too wet, too full of nitrogen potentially and too salty. For optimal pot performance, you want a soil foundation of bark fines and perlite, accented with a little peat or compost.

Thanks again Oxboy this is very helpful right now. Where do you find bark fines? c

Watching some YT videos, and many of them mention the following materials, with their own fair warning: This is what works for them and how they produced all the veggies that they did in the previous year.

builder's sand/top soil/dirt/garden soil (sometimes even not having this part, just having the next 3 items)

perlite or vermiculite (one video even mentioned both together in the same quantity)
spaghnum peat moss or coconut coir
compost (different kinds, including cow or horse manure, mushroom, vermicastings)

Then for the additives which would be in much smaller quantities for the mix, there was
garden lime
epsom salt
fish or seaweed emulsion
bone meal

After watching many and reading on the same topics, it comes down to some general guidelines, as well as adding anything specific for the type of plants you may be doing.

This year, I will be trying different mixes also, for my own knowledge and experimentation, since I have some plants growing in ground, in pots, and even seedling mixes. But for tomatoes, I added some epsom salt to the mix during planting time.

I just used Vigro potting soil due to the fact that I got 2 huge bags of it for free. I am using MG Tomato fertilizer when the plants get big enough. Time will tell how well they will do.

I went with the water retention formula of the green bag, added mushroom compost, vermiculite and will fertilize with a liquid organic called John's blend or something like that. Then I found some big bags of Black Gold...they call it natural and organic potting soil. I liked it last year. Found it at Ace for the same price as the other stuff. Mixed it with about 1/3 as much Mushroon compost and will fertilize the same.

A good container mix for tomatoes is peat, vermiculite, and perlite. Skip the bark, it's an annual so you don't need long lasting organic matter.. Vermiculite is good because it supplies magnesium which tomatoes need lots of, I'd also add greensand. You will need to fertilize the mix quite a bit, use something with relatively little nitrogen and extra magnesium. And you'll water them a lot when it gets hot.... Pick a container that is large and put some kind of support structure (cage or sticks) when you pot it up because tomato stems are weak and will eventually need to be tied to something for extra support.