Vegetables have traditionally been relegated to their own patch in the garden. With the ever-increasing varieties available these days, it's becoming easier to shift your vegetable garden to the patio. Dwarf and midget varieties also make it possible to create a vegetable garden on your windowsill.
Growing vegetables in containers has a number of advantages. It is a wonderful option for people with small spaces. Container gardens are portable; they can be moved around to suit your personal taste or to compensate for changes in light and temperature. Vegetables grown in containers are also less susceptible to soil-borne pests and diseases. Finally, it's a wonderful way to showcase your plants and keep them nearby.
The downside of container gardening is that containers need frequent watering. Containers on rooftops and exposed areas will also need to be protected from intense afternoon sun and from wind. Some vegetables don't fare well in confined spaces and a restricted root system sometimes means small fruit production.
Several factors are involved in choosing suitable containers for your container garden. As well as aesthetic decisions, there are cost, weight and watering considerations.
Vegetables grow well in terracotta pots. These pots are porous, with excellent drainage and air circulation, but they are heavy and fragile. Plastic containers and faux terracotta pots (poly-resin or polyethylene containers) are much lighter and are appropriate for situations where weight restrictions are a consideration. Non-porous containers are better at holding moisture and require less water, but don't provide the same drainage and air circulation as terracotta. Both work well, they simply require different care.
Wooden containers and whiskey barrels are popular for growing vegetables. Make sure that the wood is not chemically treated making it toxic for vegetables. Cedar, redwood, and synthetic lumber made from recycled plastic work well; they resist rotting and don't require staining. Grow bags and hanging baskets also provide good homes for vegetables.
There are many "self-watering" containers on the market these days that can dramatically reduce your watering duties. These containers have a reservoir which gets filled with water that the plants can draw on when needed. These are an excellent choice for thirsty vegetables such as tomatoes.
As for container sizes, the bigger the better. This is particularly true for vegetables that need space for good root growth: tomatoes, bush varieties of squash and cucumbers, eggplants and peppers. Three- and five-gallon containers and half whiskey barrels make good, large containers. For shallow-rooted vegetables such as radishes and lettuce, pot size is not as crucial. Pots can be 8 inches wide and 6 to 8 inches deep. To increase drainage and air circulation, standing containers on bricks or some kind of feet is always a good idea .
There are many recipes for soil mixes for container plants; find the one that works best for you. Garden soil doesn't work in containers; it's too dense, doesn't provide enough drainage and may contain soil-borne pests and diseases. Container potting mixes need to be lightweight, have good drainage, provide support and hold water and nutrients. Potting mixes are either soil-less mixes (consisting primarily of peat moss) or soil-based mixes (containing pasteurized soil). Soil-less mixes are lighter, while soil-based mixes are better at holding water and provide more support for large plants.
At planting time, add a slow-release fertilizer to the soil. Then at mid-season, begin fertilizing with a liquid feed. Reapply every 2 to 3 weeks. Because containers are watered frequently, they require more fertilizer than plants in the ground. In addition, potting mixes don't hold fertilizer as well as topsoil. Follow directions for slow-release fertilizer, slightly diluting liquid fertilizers.
Containers need frequent watering, often daily on a sun-scorched terrace. Adding water-retaining polymers or hydro gels (starch-based gels that retain water) helps decrease watering requirements. These gels hold water until the soil mixture needs it. Some people swear by them; others do not. Always follow instructions when using these products. Mulch is another effective way to decrease moisture loss. Compost, straw, shredded bark and even sea shells or pebbles can be used as mulch for your containers.
Just like other plants, vegetables planted in containers are susceptible to pests and diseases. Using clean containers and choosing disease-resistant varieties can help prevent problems. Inspect your plants for insects. If you have an insect or pest problem, try homemade remedies before reaching for store-bought chemicals. Try soapy water or combine 1 onion, 2 to 3 hot peppers, and 2 to 3 garlic cloves in a blender; add to 1 gallon of water, add a few squirts of dish soap, let sit overnight, shake, and apply with a pump sprayer.
Ultimately, good watering, feeding and maintenance practices will help ensure healthy plants. Vegetables grown on terraces may need to be covered with a shade cloth if the afternoon sun is too intense in southern or western exposures. Warm patios may be fine for heat lovers such as tomatoes, peppers and eggplants. Lettuce and many root vegetables will also need some protection.
Finally, the fun begins. What will you plant? Loose leaf lettuce, tomatoes, peppers, eggplants, zucchinis, bush beans and cucumbers do well in containers. There are plenty of tomatoes to choose from--dwarf varieties, cherries, and determinate (more compact) varieties all do well. Try 'Patio Princess', 'Tumbling Tom', 'Husky Gold', 'Sweet 100', 'Roma' and 'Better Bush Improved'. For small, disease-resistant varieties of bush cucumbers, try 'Salad Bush', 'Spacemaster', or 'Fanfare'. Watermelon 'Bush Sugar Baby' grows on 3 1/2-foot vines that can be trellised. How about cantaloupe 'Honey Bun' or pumpkin 'Baby Bear' and the white 'Baby Boo' for the adventurous gardener? Or carrot 'Short 'n Sweet' and 'Little Finger' intermingled with 'Baby Oak' lettuce for the conservative gardener. There are plenty of choices for everyone.
Your Farm in the City by 
The Vegetable Gardener's Container Bible by 