I have six containers, two feet high and 14 inches wide, each with a tomato plant. Of the six only one is fruiting. The soil is a combination of black gold, moo-doo and fully composted soil from an old compost pile.
Meanwhile the half dozen plants I have in the backyard, in a mix of moo-doo, backyard compost soil is doing signficantly better. The plants on the balcony receive marginally more sun.
Why do you think the balcony plants aren't doing so well?