I have terrible clay soil and want to try growing tomatoes, peppers, carrots and maybe corn in Grow Bags in the spring. What is the best size of bag to use? I plan to use Al's 5:1:1 mix as the planting medium.
The size of bag will vary. 15-25 gallons for each tomato plant - depending on variety, and 4-5 gallons for each pepper plant is a good starting point. For carrots and corn, bag size would depend on the number of plants you intend to grow in each bag.
I really think you'll be happier with something other than the mixes I suggest for conventional containers, though. Hydrologically speaking, grow bags are mini raised beds. Because water behaves differently in grow bags - that, because the earth below acts continually as a giant wick and perched water isn't normally a problem - a heavier soil that holds more water against the wicking action of the earth is desirable. Should your intent be to site the bags on a surface that doesn't absorb water (deck, concrete slab ...) then disregard what I just said and treat them like you would containers ... in which case the 5:1:1 mix would be much more appropriate.
Thanks once again for the good advice. I do plan to site the grow bags on my patio so I'll be able to benefit from the 5:1:1 mix. I know I'm wishing my life away but can't wait to grow my veggies (my first time). I live in a rural southern Utah area (close to Zion National Park) and have lots of wild critters including, of course, mule deer galore so the only other thing I'll have to take care of is erecting a deer proof fence with fence posts and the mesh fencing. It seems to work well in my neighborhood. Onward, ever onward !!!