Contain those vegetables

Space, sun, water
Obviously a container is limited in size and space. Choose vegetables that grow in small areas such as carrots, radishes, lettuce, and kale. Or you can choose a plant that bears its fruit over time, like tomatoes and peppers. Limited space does lend itself to dwarf or miniature varieties, but as these do not produce as well as standard varieties, so you may want to try both. Also some companies are beginning to produce varieties specifically bred for container gardening (particularly cherry tomatoes), so have a look at your local gardening centre.

If you are growing vegetables for their fruits, you will need at least 5 hours of direct sun everyday (and 8-10 is better). One of the nice things about containers is that you can position them in the sunniest spots (rooftops are one example for urban dwellers). You can also help to enhance light in the area by surrounding your container with reflective materials – aluminum foil or white-tinted rocks. If you don't have a site with that much light, root crops and leaf crops can perform well in partial shade.

Watering is particularly important with container plants. Because there is not all that much soil, containers can dry out quickly, especially on a concrete surface in full sun. Small pots dry out more quickly than larger ones, as well. You may need to water every day or even twice a day. Water until it runs out of the drainage holes – obviously, if you are gardening on a balcony you will need to have trays under the plants to ensure you aren't dripping on someone's chairs! In cooler weather, you will need to watch for over-watering as roots can rot. Clay pot or other porous material are helpful to avoid rot, but may require additional water.