Expert tips for growing tomatoes in your garden

“I want to try growing tomatoes in my garden this year and would like some advice on how to be successful in doing so.”

— Larry Zar, Highwood

There are some basic practices to follow that will help ensure your success in growing tomatoes.

Garden centers have lots of tomato plants for sale now, so it should be easy to find good quality plants. Determinate tomato varieties (meaning they have a determined, defined growing height) grow to 2 to 3 feet tall and generally do not require staking — thus are good for small spaces and containers. They tend to provide many ripe tomatoes earlier in the season, and at the same time, with less productivity in the latter part of the season.

Indeterminate tomatoes will continue to grow big and need cages or stakes. They produce fruit all summer and into fall, when frost kills the plants. Fruit production slows as the days become shorter and colder in fall before a frost.

Look for tomato plants that have dark green leaves and are short and stocky with strong stems. They should not have any flowers or fruit forming unless they are established plants growing in a large container. I prefer growing heirloom varieties because of the large number of different types. The plants dry out quickly at home, so be sure to watch them closely for water until you can plant them.

It is very important to wait until temperatures stay consistently warm before planting tomatoes, as cold soil and air temperatures can set their growth back dramatically. Memorial Day weekend is generally a good time for planting tomatoes in the Chicago area, but use the weather as your guide, since timing can be earlier or later depending on spring weather. I saw tomatoes for sale at the end of April and wonder how these plants fared without the gardeners employing specialty growing techniques to offset the cold weather.

Tomato plants need to be in a bed with full sun for best results, since light shade adversely affects the fruit production. I have successfully grown tomatoes in beds that were shaded in the morning with full sun in the afternoon. The soil should be well drained and amended with compost.

Plant the tomatoes deep by burying most of the stem. Remove any of the lower leaves that will be underground after planting. The plants will form roots along the stem. Planting deeply also helps stabilize any transplants that happen to be taller and spindly. Provide plenty of space — at least 2 feet — for each plant to develop, as many tomatoes will get large. Install tomato cages shortly after planting to help protect the young plants and provide support for them.

Consider rotating crops with those that are unrelated in order to break the life cycles of insects and diseases if you can. Peppers, eggplants, potatoes, and other plants in the Solanaceae family are related to tomatoes, so they should not be planted during the rotation years. This can be more difficult if you have a small space, so consider your crops carefully and experiment with different combinations.

For more plant advice, contact the Plant Information Service at the Chicago Botanic Garden at plantinfo@chicagobotanic.org. Tim Johnson is senior director of horticulture at the Chicago Botanic Garden.