- Properly fertilizing your plants is essential for success. How much and how often depends on your growing medium, the quality and nutritional value of your compost (if used) and the type of vegetable.
- Some potting mixes contain slow-release fertilizer. In this case, vegetables won't need feeding for eight to 10 weeks after planting. If you're using good-quality soil, compost and organic fertilizer, you can wait four to six weeks. Then add liquid fertilizer every two weeks or, if plants need it, once a week. Exceeding the amount recommended on the package can burn or even kill the plants.
- Even better: feed your plants with composted manure (any kind is fine except for chicken, which is too high in salt) or compost tea. (To make tea, suspend a cloth bag containing one part compost or composted manure into a pail with five to eight parts water. After one day, the water will turn dark brown; dilute to the colour of weak tea before using.)
A regular watering routine is crucial to successful growing. Containers dry out quickly and need to be checked at least once a day. On sunny, dry days or in very hot conditions, such as those found on rooftops, they may need to be checked twice daily. Even after a rainfall, don't assume the container has been sufficiently watered, as leaves can prevent the water from reaching the soil.
Water when the soil feels dry 2.5 centimetres below the surface. To help prevent problems with mould or fungus, water in the morning. If you must water at night, avoid wetting the leaves.
When you water, make three passes with the watering can or hose (holding each time until water reaches the top of the pot). Initially, the water will likely run right through because the soil is dry. If the soil has separated from the pot around the edges after the first pass, gently press it back against the inside of the container. Water a second time until water once again drains out the bottom. The third time, thoroughly soak the soil.
Watering is more challenging if your containers rest on saucers, as roots can rot if a plant sits in water. Remove any water that hasn't been absorbed after 20 minutes—don't forget to check plants after a heavy rainfall, too. Choose saucers with raised supports or put a layer of pebbles, gravel or river rocks on the bottom of the saucer.