Should You Prune Tomato Plants?

Pruning tomato plants is an increasingly common practice as bio-intensive gardening practices like vertical and square foot gardening become more popular. Some wonder whether they should prune their tomato plants too.

Determinate or Indeterminate 

Before deciding to prune your tomato plants, determine whether they are a determinate or indeterminate variety. Determinate varieties grow to a determined size, around 3-4ft tall, and produce a determined amount of fruit. In addition, the fruit on determinate varieties is often ready sooner and all at once. 

Compared to indeterminate varieties which grow over 6ft tall if you let them. These varieties produce later in the season but will continue to produce until they die. 

To stop these varieties from growing too tall, you can top them. This consists of cutting the main stem of the plant at the desired height. 

Both varieties produce off-shoots or suckers. When we prune tomato plants, these suckers are what we remove. By removing the suckers we are removing any potential fruit that would have been produced from that growth. 

This is okay for indeterminate tomato plants because they will keep growing and producing. Since pruning can increase the life of a tomato plant, it may produce about as much or more than if it weren’t pruned. 

Yet, pruning determinate tomato plants this way will reduce your harvest, because they only produce a determined amount of fruit.

Benefits of pruning 

Increased Airflow

Increased airflow helps prevent pests and disease and keeps plants healthier, longer. 

Decreased Pests And Disease

Due to the increased airflow and the distance of the leaves from the soil, pruned tomato plants stay healthier longer. If you have an indeterminate tomato plant, this means it will produce longer. 

More Plants

When you prune your tomato plants, they will be more compact and will grow vertically rather than bush out. This means you can space them closer together. Since you have more plants, you won’t miss the fruit that would have grown on the pruned suckers, and may even get more!

Keeps Plants Tidy And Manageable

Pruning your tomato plants will make any fruit that grows on them more visible. It will also make them easier to water, and inspect for pests and disease.

Drawbacks of pruning

It’s Time Consuming

To maintain your pruned tomato plants to one stem, you will have to go out every 1-2 days and check for suckers. At the height of the season, suckers can go unchecked, leading to dense and unwieldy plants. 

This may not affect plants following normal spacing and staking recommendations. But, if you space your plants closer together then you may end up with plants that don’t have enough airflow. Leading to more pests and disease.

Can Reduce Yields 

Some people argue that pruning indeterminate varieties leads to smaller yields. This may be true for particularly short growing seasons. In short growing seasons, unpruned tomato plants may not live long enough to succumb to pests pressure and disease. 

For longer growing seasons, having more plants that grow up to 6 or 7 ft tall could yield greater harvests.

If you are in a shorter growing season, are growing determinate varieties, or want a more hands-off approach to gardening, pruning your tomato plants may not be the best way to go.

But at the end of the day, to prune or not to prune your tomato plants comes down to personal preference. 

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