I would start fresh and turn the soil you presently have in containers into the compost pile or the garden. The sapwood/gardensoil mix is a recipe for soil compaction and even at only 1/3 of the mix, it will impact drainage and aeration. In addition, if you're asking about using this mix as part of your next growing season's soil, you might consider that soils will collapse (particles break down) much quicker in the second growing season. Of course, if there are economic considerations, you work with what's required.

I don't use vermiculite in container soils, choosing a more stable counterpart - perlite. The vermiculite has a tendency to shrink/compact over the growing season and hold more water than what suits me in zone 5-6. Both perlite and vermiculite are heat-expanded mineral products, sorta like mineral popcorn.

I'll leave a link that should be helpful if you want to wade through it. Also, try here if you wish to read more. Cut & paste to browser: http://forums2.gardenweb.com/forums/load/contain/msg0321395926870.html

Best luck!

Al

Here is a link that might be useful: Container soil info

Thanks Al!
I'm sure I'll have more questions as I go, but this is a great start. Thanks again.

I use the 3 cubic feet bags of container soil in all my containers (about 25 containers).

Everything did awesome in the container soil this year and is still doing great while my neighbors in the ground gardens are not doing so great.

It cost a bit to buy the soil but it can be rejuvinated every spring. Dump out your container and get some fresh container soil, it's worth it.