Taming Your Tomatoes

To Prune or Not to Prune

One of the joys of gardening is obviously watching our plants grow. Sometimes with tomatoes they show off by their growing power by turning into a tomato jungle. One year my plant swallowed up a trusty garden tool and it reappeared at the end of the season. Although it may be tempting to let them grow and grow, it is much better to prune your indeterminate tomato plants. We’d rather them turn their attention to actual tomato production instead of showing off how big and bushy they can get.

If you are like some gardeners and afraid to hack away. Have no fear, you will be rewarded with better crops and healthier plants.

Plants being attacked by tomato diseases is something we have all heard from our fellow gardeners during the summer. Pruning your tomato plants thins out the foliage to introduce more air flow and sunlight, which can help with disease issues.

Your tomatoes will thank you by ripening if you prune and allow more sunlight to reach them. That juicy sweetness needs sunlight to photosynthesis in the tomatoes to allow the plants to make carbohydrates that are turned into flavor components such as sugars, acids, and other compounds.

There is some thought that pruning your tomato plants will encourage them to produce more tomatoes overall by redirecting that energy into fruit production vs growing more leaves and stalks. A properly pruned and supported single-stem tomato plant presents all of its leaves to the sun.

First off, what’s the difference between “indeterminate” and “determinate” tomatoes?

Determinate tomatoes, or also referred to as “bush” tomatoes, are the varieties that grow to a compact height of around 3 to 4 feet. Determinates will stop growing when fruit sets on the top bud. All the tomatoes will ripen at approximately the same time, which is usually over period of 1- 2 weeks. They require a limited amount of staking for support and are usually suited well for container gardening.

Indeterminate tomatoes will continue to grow and produce fruit until they are finally killed by frost. They can reach heights of up to 12 feet although 6 feet is normal. Indeterminates will bloom, set new fruit and ripen fruit all at the same time throughout the season. They will require substantial staking for support or they will most likely topple over.

How to Prune

First you want to make sure that you are ONLY pruning Indeterminate plants. If you are unsure please do some research before you start pruning. Secondly, you should wait until your plants are about 2 feet.

Step One:

You will first want to identify the main stem of your tomato plant. If you stand in front of your plant you should be able to follow the main stem all the  way up to the top of the plant. This is the main growing part of the plant that allows it to continue to grow taller. You DO NOT want to cut this off while you are pruning.

Step Two:

Now you will want to find the tomato clusters and the flower clusters.



Step Three:

Now you will want to start looking closely at your tomatoes leaves. Look where your leaves are connected to the main stem. Often between the main stem and the leaf there will be what is called a “sucker”. The sucker will grow to have its own leaves, flowers, fruits, and suckers. It’s basically like a whole new tomato plant growing out of the original plant.

Step Four:

Look for the lowest flower of fruit cluster on the plant. Keep your hand on this and look for the sucker right underneath this cluster. This is one of the strongest suckers on the plant because the amount of energy being sent to help produce the fruit above it. This is one of the suckers we are going to KEEP. The next step is to remove suckers you find on your plant. You might not want to remove every sucker as this will cut down on your overall production. Step Five:

This is optional, but I remove any leaves that are touching the ground. Most tomato diseases come from the soil, so this may help limit your plants contact with the soil. Also any leaf that looks sickly or yellow does not help the plant, take it off.

Step Six:

This a great time to either put tomato cages or trellis. I highly recommend staking and trellising your tomatoes. The small round tomato cages usually can not handle the size of most of our plants in the garden. My plant is in prior years have gotten so big that they took down the cage. Also cages make it hard to prune and the fruit ends up being buried inside the cage and not getting enough sunlight.

A few tips about pruning:

  • Never prune when your plants are wet, Touching wet leaves can transmit disease.
  • The best time to prune a sucker is when they are small enough to be pinched off. This reduces the wound size and saves the plants energy.
  • If you didn’t notice a sucker and it is now the size of a pencil, leave it alone as you may damage the plant.
  • If you do use tools, make sure they are clean. It’s a good idea to wipe them down with rubbing alcohol to ensure they are disease free.
  • Wait until the plant is about 2 feet tall
  • If you are new to pruning, be prudent. Leaves create shade for fruit, which prevents sun damage. Leaves also make food for the plant, including sugars, resulting in energy to produce more quantities of sweeter fruit.

Pruning is certain not necessary and some gardener disagree with the theory of pruning. So, do your research and see what is right for you and your garden. You will have bountiful tomatoes even if you don’t prune.

Last year I was more aggressive in my pruning and produced high quality yield, but not as many tomatoes. This year I will not go after every sucker. I don’t want to turn my tomatoes into bonzai trees! We are looking to give your plants more light and more air, so be conservative if pruning makes you nervous.

Happy Gardening!
Mary Church

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