The trick with container gardens is that you have to fertilize them. Add slow release fertilizer to the containers about once every three weeks throughout their growth and production. Use large containers for best results. I used containers to grow tomatoes outside of my regular garden this year because we have a potato blight problem that effects tomatoes that are not well protected. I used high quality fish compost mixed with soil in my pots as a base to plant the tomatoes, and I use a low nitrogen fertilizer to feed them because the fish compost provides enough nitrogen. You can plant potatoes this way too, and they are very productive and the easy to grow. On the subject of compost, I use a compost pile for when it is not convenient to dig my garden, and I add garden soil to the compost pile to condition the soil for later use, and it keeps the smell down and the rodents out. Compost is best dug directly into a garden where plants can use the nutrients as the organics break down, and the worms work the soil. This spring I dug two long trenches in my garden, filled them with organics (grass clippings, weeds, last years corn stalks, and kitchen waste), and mixed some soil (includes micro organisms) into the organics, and then topped this mix with a 6 inch layer of the remaining soil. I planted my squash and cucumbers on top of this and mulched them. This would work well with tomatoes. Digging raw compost directly into a garden builds soil structure because micro organisms and worms work the organics with the soil building a better soil structure for plants. This is particularly useful in areas with clay soils. Also, plants can take advantage of more of the nutrients before they are lost to other organisms or as gaseous forms to the atmosphere, which is what happens as organics break down and are processed. Worms help to work compost, but they are more important in a garden as they form the soil (passed through them as feces) into small pellets that makes for loose well drained soil. This is a good reason to dig raw compost directly into a garden. A well worked compost pile, however, is an awesome planting medium, and can be used in pots. Good luck with your tomatoes.