Containers on a sunny balcony or patio offer an excellent alternative to traditional gardening. This article walks you through container and soil choices, crop selection, how to water and fertilise container plants, and additional pointers about how to make your container garden a success.
Locating a container garden
Containers should be placed in a sunny location on a balcony, patio or similar outdoor location. Your container crops will need at least 5 hours of direct sunlight a day, and ideally 8 to 10 hours.
Containers can be made from a variety of shapes and materials including: plastic or terracotta pots, cedar (preferably not redwood because it is in short supply) planters or window boxes, barrels, cut-off milk jugs, or even recycled polystyrene coolers. Make sure the containers are made from untreated wood and not treated with creosote or pentachlorophenol (Penta) wood preservatives that are highly toxic.
Containers: Bigger is better
The larger the container the better. Gardening containers require more soil than indoor plants, at least 2 to 3 fists deep, preferably more. Generally, most crops need a container that is twice the size of the fully grown crop at harvest.
Packaged potting soil is preferable because it has been mixed for this purpose, and is relatively lightweight. Soil straight from the garden is much heavier. Soilless mixtures, as the ones used to start seedlings, do not readily support vegetable roots. Also, unless you add compost or soil, because they are sterile soilless mixtures lack certain nutrients that are needed to grow vegetables.
Garden on wheels
Containers, when watered and filled with quickly growing plants, can become heavy and cumbersome to move into or out of sun, or out of the way from strong wind and storms. Adding casters to your containers or wheels to your container platform can make this chore easy.
Selecting container crops
You should select crops that have modest root systems: eggplants, peppers, cherry tomatoes, lettuce, onions, carrots and herbs. Cucumbers and sweet potatoes can work, too. Remember that heavy and tall crops are more likely to be knocked over. For this reason, you can grow cherry tomatoes but not large tomatoes. For more information about growing a specific crop in a container, see individual vegetables and fruits.
Varieties tailored for containers
With the enormous recent growth in container gardening, seed companies and nurseries are offering an increasing number of varieties with smaller root systems and less height specifically for containers but with the same size fruit.
Frequent watering and shielding needed
Containers need daily or twice daily watering. Every time water the container until water seeps out the drain holes. Because of the relatively small amount of soil in a container, even when it rains, the containers will need to be watered often, usually daily. Lots of direct sun, heat reflecting off a concrete patio, and wind all contribute to quickly drying out a container.
Mulch conserves water
Putting 1 or 2 thumb-widths of mulch on top of the container soil will help retain moisture. For more information see 'Mulching' in our Soil article.
Most prepared soil mixes include enough fertiliser to support plant growth for 8 to 10 weeks. If your crop grows for longer periods, use a water-soluble fertiliser per the recommendation on the package, usually every 2 or 3 weeks. Too much fertiliser can stunt or kill a plant.