University of Illinois Extension

Growing Vegetables in Containers

Would-be vegetable growers in urban areas have alternatives to the challenges to outdoor gardening, said Maurice Ogutu, University of Illinois Extension horticulture educator.

“If you have a passion for vegetable gardening, you need not give up as there are alternatives such as growing vegetables in containers,” said Ogutu. “Vegetables and even flowers and herbs grown in containers can be placed or moved to any spot such as windows, balconies, patios, and doorsteps where there is full sun.

“There are several types of containers that can be used for growing vegetables. These include polyethylene plastic bags, clay pots, plastic pots, metallic pots, milk jugs, ice cream containers, bushel baskets, barrels, and planter boxes.”

Ogutu said it is very important to use containers that can accommodate the roots of the vegetables you want to grow as the vegetables vary in size and root depth. The container also needs to have good drainage, and should not contain or be made up of chemicals that are toxic to plants and human beings.

“The vegetables suitable for container gardening are the ones that require small space, particularly the dwarf or determinate types, or bear fruit or other harvestable parts over a longer period of time, require full sun or partial shade, and plants that will make the landscape look beautiful,” he said.

He recommended using potting mix (soil-less media) in vegetable container gardening as these mixes are light, disease-free, weed seed-free, and have good drainage.

“Some potting mixes have pre-mixed plant nutrients, but it is very important to read information on the label about how long the pre-mixed nutrients will support plant growth before you start applying fertilizers,” he said. “You can also make your own two bushels of potting mix by using the following recipe: one bushel of shredded sphagnum peat moss; one bushel of vermiculite; 1 1/4 cups of ground limestone; one-half cup of 0-20-0 phosphate fertilizer or one-fourth of a cup of 0-45-0 fertilizer; and one cup of slow release granular fertilizer such as 5-10-5.”

Most vegetables grown in the backyard can be grown in containers, although container diameter and depth need to be considered. The plant density (number of vegetable plants per pot) depends on the individual plant space requirement and rooting depth.

Ogutu suggested minimum container sizes and the varieties of vegetables:

Vegetables require full sun, except for the few that are grown in partial shade. Most fruit-bearing vegetables such as tomatoes, peppers, cucumbers, squash, and eggplant require full sun. Leafy vegetables such as lettuce, cabbage, collards, mustard greens, spinach, and parsley can tolerate partial shade better than root vegetables such as turnips, beets, radishes, carrots, and onions.

“Put the containers in a spot where vegetables can receive at least six hours of sunlight per day,” said Ogutu.

Plants grown in containers need frequent watering because the containers dry quickly. Watering on a daily basis is necessary to provide adequate moisture for plant growth.

“Apply enough water to reach the bottom of the container and allow the excess to drain out through drainage holes,” he said. “Avoid wetting the leaves when watering as this will encourage the development of foliar disease.

“Do not allow the containers to dry out completely between watering as this will lead to flower and fruit drop. Do not over water as the container will become waterlogged and the roots will lack oxygen, leading to poor growth and eventual plant death.”

Ogutu noted that container-grown plants require more frequent fertilization than field-grown plants because of the limited space within the container.

“Nutrient solution can be made by dissolving soluble fertilizer such as 10-20-10, 12-24-12, or 8-16-8, in water following label directions,” he said. “The nutrient solution is applied once a day when the plants are watered. Frequency of watering may vary with vegetables, but once a day is adequate.

“Leach the unused fertilizer nutrients from the potting mix once a week by applying tap water. It is also important to water occasionally with nutrient solution containing micronutrients such as copper, zinc, boron, maganese, and iron. Follow label directions in order to give plants the right amounts.”

Vegetables grown in containers can be still be attacked by insect pests and disease. Ogutu recommends inspecting the plants periodically for insect pests and diseases. Use recommended insecticides and fungicides or contact your local Extension office for assistance.