Pruning Tomato Vines

A great many tomatoes are available to home gardeners, either as seeds or seedlings. We are already well into the growing season, so if you enjoy growing tomatoes you are probably already past the stages of selecting a variety or planting seeds or seedlings.

If you are already skilled at pruning your tomato plants, and doing the job in a timely manner, you will not need to read this column.

For the rest of us, let us review the pruning process, with an emphasis on corralling a runaway tomato vine.

The first bit of knowledge about growing tomatoes is that the multitude of cultivars includes just two types: determinate and indeterminate. The determinate plants develop a number of stems, leaves, and flowers, as predetermined by their genetics, and then stop growing. The fruits (actually berries according to the experts) all ripen at the same time, relatively early in the growing season. Pruning of these plants only reduces the harvest.

The indeterminate plants continue to grow and produce stems, leaves, and fruits throughout the season. These are the plants that need controlling.

Expert grower Frank Ferrandino, writing in Kitchen Gardener Magazine, warned, “Left to its own devices, a vigorous indeterminate tomato plant can easily cover a 4- by 4-foot area with as many as ten stems, each 3 to5 feet long. By season’s end, it will be an unsightly, impenetrable, disease-wracked tangle.”

I am growing three tomato plants this year, all of which are the variety, Super Sweet 100, a popular bite-size tomato. I grew one of these plants last year, watched it produce a bounty of very tasty little tomatoes, and develop into the tangle that Frank F. warned about.

Long after I had cleared the bed, a new spring arrived and several seedlings of Super Sweet 100 appeared. I replanted three of the best, determined to control the plant better.

The goals of pruning a tomato plant are to promote larger fruits (not really an issue for cherry tomatoes), keep the plants tidy, and keep the plants off the ground to minimize the potential for disease. The Super Sweet 100 is a disease-resistant variety, but keeping the plant tidy and off the ground still seems worth the effort.

The basic pruning technique is to remove side shoots, called suckers, that grow in the crotch (axil) between the main stem and the side stems. These suckers can produce fruits, but they tend to develop later than the primary fruit-bearing stems and reduce the plant’s vigor.

Tomato plants grow rather quickly, so the removal of suckers is a weekly task. When the suckers are very young, they can be snapped off without the use of tools.

Despite my nest intentions, my plants were soon well on their way to the predicted tangle. This condition inspired an experiment, which took the form of brutally cutting back branches that were sprawling in all directions and in several instances producing little or no fruit.

Super Sweet 100s (green)

More systematic training surely would have been better, but this approach was really the only option at the time. I expect and hope the plants will shrug off my abandonment of best practices and produce another bountiful harvest of sweet, small fruits.

Those fruits are mostly green, still, but have plenty of time to ripen. I’ll try again next year to prune by the book.

 

For a helpful demonstration of pruning tomato plants, see Fine Gardening magazine’s video recording on YouTube.

For more about all aspects of growing tomatoes (selecting, planting, training, harvesting), see “All About Tomatoes” on Vegetable Gardener magazine’s website.

Leave a Reply

Your email address will not be published. Required fields are marked *