You and me are in the same boat!! I have done peppers, garlic, and herbs in pots, but as for a dwarf tree, from what my nursery tells me, you would want a really big pot like 3 feet wide to accommodate the roots growing, other wise they will break your pot. My tomatoes didn't do too well in a pot, but I think a lot of it was under watered and too hot, because they did really good in the ground. A lot of my garden is in the flower beds around my apartment. You can also do blueberries as long as you make sure that there are holes in the bottom, I forgot to check my pot and wasted $30 of blueberry bushes due to root rot. Strawberries do wonderful in containers, I don't get any but my son does, and they are going nuts, and you can just keep winding the runners inside the pot and it will keep making new starts. I have heard that lettuce does really good in containers, and you can use the little window box planters for them, and I think they have some if you have a railing that you can hang off of the railing. You might be able to do potatoes in a food grade 5 gallon bucket too.