As one of the most popular varieties of vegetables to grow, tomatoes are a favourite in the garden. As such, some of the most common questions we get revolve around caring for tomatoes. In this week’s tip, we’ll go over what tomato suckers are, why and when you should be pruning these back, and how you can get maximum fruit production in our relatively short growing season. Keep in mind this advice is geared towards indeterminate tomatoes, of which 95% of all backyard tomatoes of all sizes fall into this category. Unless you are growing a dwarf variety or special “patio tomato” variety that grows to only a small size, keep on reading for information on suckering your tomatoes.

What Are Suckers?
Suckers can be though of as “secondary” branches of a tomato plant. They form at the joint where the horizontal tomato branch meets a vertical tomato stem. If left to grow, these suckers will become their own vertical stems with their own horizontal branches and their own suckers growing out of the joints. Essentially, the plant can grow exponentially as new suckers keep on growing as the plant develops. Here’s a picture of a tomato sucker growing in the joint of the plant.

tomato sucker highlighted
Photo: Tomato Suckers Highlighted

Why Pinch Them Off?
Gardeners pinch off suckers to help control plant growth. If left to grow naturally, the plants will often get too large and unwieldy, limiting airflow and sunlight to all areas of the plant (thus increasing the chances of diseases/insects), and making it difficult to harvest.

By training your plants to grow with only 1 or a few vertical stems, it will be easier to shape the plant as well as stake it to keep the leaves and fruit from touching the ground.

Towards the end of the outdoor season, we recommend you pinch off all suckers to encourage the plant to put as much energy into ripening up existing tomatoes on the vine, instead of allocating some energy to developing new branches and stems.

What If I Leave Them?
Leaving tomato suckers to grow won’t harm the tomato plants. In fact, some gardeners argue that removing suckers may reduce the overall potential of the plant by reducing the amount of leaves available for photosynthesis. If leaves are the engines that produce flavour, growth, and energy of the plant, removing these leaves/potential leaves may reduce the complex flavours in tomatoes while also exposing the fruit to the potential of sun scald.

Should I Sucker The Tomatoes?
In general, we recommend letting your tomatoes grow to have 1-3 vertical stems upon which the majority of the fruit and leaves will develop. Once the main stems are growing and identified, pinch off suckers early as they develop and especially towards the end of the season when the weather starts to cool down. While this may produce a slightly taller tomato plant (at the expense of a wide/bushy plant), we find it easier to manage and easier to harvest and reach into get all the fruit with a taller and narrower plant than a shorter and bushier plant.

For help with your tomato plants, including pruning advice, harvesting and staking, check out some of our gardening services.

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