Container gardening is a popular method when soil space is limited, such as in areas with poor soil or even areas with no soil at all such as apartment balconies or rooftops. Container gardens are freer of soil-borne diseases and nematodes. Almost any plant that will grow in the ground can grow in a container as long as the container is large enough to hold the plant's root system.
Select containers that are the correct size for your plants. Tomato plants will do well in large plastic containers or even 5-gallon storage tubs. A potato plant, garlic or watermelon will do well in a half-barrel planter. Do not use containers that are too large for the plant. These containers can hold too much water in the soil and promote root rot in vegetable plants.
Purchase commercial potting soil that has been sterilized, or mix your own soil using 1 part peat moss, 1 part compost and 1 part perlite. Never re-use potting soil to prevent the spread of diseases.
Purchase seeds and transplants from nurseries or garden centers.
Place a pottery shard over the drainage hole of a container and fill the container with soil. Leave an inch of space between the soil line and the top of the container so that the plant can collect water.
Open a planting pocket in the soil for seeds or transplants. The planting pocket should be twice as wide for the root ball of transplants, but no deeper. The hole for seeds should be twice as deep as the seed at its widest diameter. Place the root ball of the plant or the seed into the hole and cover with soil.
Water the plant or seed so that the soil remains as damp as a wrung-out sponge. Check the container daily and water as needed. Soil in container plants will dry more quickly than soil in the ground. Add a balanced (10-10-10) liquid fertilizer to the water based on the instructions on the fertilizer packaging. Fertilizer application rates will vary among brands.
Place containers where the plants will receive the required amount of sunlight. All vegetables, fruits and herbs require between 6 and 8 hours of sunlight daily. Some flowers and ornamental plants such as impatiens and hostas require considerably less sunlight.