5 tips for ... growing tomatoes in pots
Here are some tips for potted tomatoes.
1. Give them room. Most slicing tomatoes need a 5-gallon pot, though you can find cherry tomato plants that will do well in hanging baskets. Some varieties are specially bred to stay small enough for a tight container ('Micro Tom' is just 7 or 8 inches high). Make sure the container has drainage holes.
2. Use good soil. In pots as in the ground, tomatoes need well-drained soil with lots of organic matter. Gensch likes to add a little bit of lime to provide extra calcium (which helps prevent blossom end rot). Put a couple inches of gravel in the bottom to stabilize the pot, because when the fruit sets the plant will be top-heavy. And add stakes or a tomato cage for support when you plant.
3. Plant deep. Leave only the top two or three sets of leaves above the soil line. The part of the stem that is buried will sprout roots that help support and strengthen the plant.
4. Fertilize properly. Choose a fertilizer that is not heavy on nitrogen (which fosters leaves at the expense of flowers and fruit). Phosphorus (for roots) and potassium (for blooms) are more important. Whether the fertilizer is organic or not, the guaranteed analysis of major elements on the label should be even, such as 3-3-3, or higher on the last two numbers, such as 4-6-5.
5. Water regularly. Tomatoes need consistent moisture; swinging between extremes of wet and dry can do them in. Be prepared to water daily. Gensch says water-holding gels (sold in crystal form and mixed in the soil) are especially good for rooftop tomatoes.