Tomatoes – Pruning

I love growing tomatoes mainly because I love eating tomatoes.  There is nothing better than a warm tomato, picked from the vine on a hot West Texas afternoon.  What a treat to stand in the garden with tomato juice and seeds dripping down your chin as you savor those complex tastes.  Yum!

For some people growing tomatoes in West Texas proves to be nothing but frustrating.  Much like anything else in gardening, successfully growing tomatoes is more of an art than a science.  Most of my experience comes from the trial and error school.  Hopefully, some of what I write will help others be more successful with less failure.

One of the things I have learned working with tomatoes is the need to be more proactive in my maintenance and care of the plants, specifically in keeping the plants pruned properly to maximize the production of fruit.

tomatoes - pruning diagram

The First Big Rule

The key to pruning tomato plants starts with one big rule.  You must know and understand what variety of tomato you are growing.  Tomatoes come in two varieties, determinant and indeterminant.  Determinant varieties only produce fruit once.  Indeterminant varieties continue to bloom and produce fruit their whole growing lives.  You should only prune indeterminant varieties.  If you prune indeterminant varieties you may reduce your harvest rather than increase it.

Why Prune.

The big reason is to get more yield from your plants.  Pruning can also increase airflow in and around the plants making them healthier and stronger. A healthier stronger plant produces more fruit over its lifetime.  Less density in the green portion of the tomato plants makes it easier to spot disease or pests before they can become a major problem. 

Pruning can also mean bigger fruit at harvest and can encourage the plant to ripen fruit quicker. Pruning, in some circumstances will allow you to plant closer together.  Most pruned tomato plants are trellised or supported on some vertical support system that allows the vines to grow tall.  Without the horizontal spread and with less green plant material to support, the tomato vine can direct more energy to fruit production. 

When to Prune

tomatoes - pruning staked tomatoes

At Planting

When you get ready to move your transplants into the ground or whatever media you are using to grow your tomatoes, remove a few of the lower leaves and bury the plant deep enough into the soil to cover the leaf nodes where you removed the leaves.  Each of these leaf nodes will begin to produce additional root structure, giving you plant a head start.  If we are planting in soil, we also like to sprinkle a little dry molasses and worm castings into the hole before we place the plant.  In some cases we also add a bit of Epsom salts to the mix.

tomato - pruning trench transplants

If your transplant has already flowered, remove those blooms.  Setting fruit is a major drain on the plant’s resources.  Removing any blooms (or set fruit for that matter) that are on the plant at transplant time will allow the plant to direct its energy to build root structure and leaf growth at this early stage of its development.

Sometimes tomato plants will become tall and leggy in the greenhouse.  The easiest way to deal with this is to perform what I call “trench transplants.”  Prune away the leaves from the lower portion of the transplant.  Leave a cluster of leaves and stems at the top of the plant.  Instead of digging a hole, dig a trench and lay the plant stem and root ball in the trench and backfill carefully.  Every leaf node that you pruned should begin to produce root systems, and the remaining leaf structure will flourish.

Early to Mid Season

If your early season plants try to bloom before they are 12 to 18 inches tall, prune away those blooms.  Your plant is still developing the root structure and needs to put its energy where it will do the most good later in the season.

Pinch or prune away and leaf suckers that develop on the plant during early growth.  Suckers are the little side shoots that develop where the leaf stem attaches to the main growing stem.  These can also develop at the base of fruit clusters.  Removing suckers will be a season-long job.

Late Season

When fall is approaching and that first freeze is on the horizon, if you are like me you begin to panic because you can see all of that unripened fruit on your tomatoes and you don’t want any of it to go to waste.  Pruning judiciously in late season can encourage your tomato vines to riper fruit quicker.  Late season pruning is done by removing the growing tip of each main stem on your plant.  This method of pruning is called topping and effectively stops the plant from flowering and setting fruit.  The object is to force the plant to direct all of its energy to ripen the fruit already set.

Options

Some of you may not have the option of pruning your tomatoes as I have described because you don’t have the means to support or trellis your tomato plants.   If you use cages to support your plants there are a few other techniques that can be used to enhance the fruit production of your tomatoes.

If you are growing tomatoes using cages, keep the lower leaves and stems pruned so that they don’t touch the ground.  Leaves lying on the ground are an open invitation to pests and diseases.  I suggest pruning your plants so that the lowest leaves are no closer than 12 inches to the ground.

Tomatoes - Pruning caged tomatoes

Tomatoes grown in cages tend to become tightly packed in the cage.  Tightly packed leaf growth inhibits airflow and provides a great habitat for insect pests.  Prune the interior parts of your tomato plants to improve airflow inside the cage.  When pruning caged tomatoes try to avoid pruning stems immediately adjacent to fruit clusters.  Leave the leaf structures immediately above and immediately below the fruit cluster.  Studies have shown that most of the sugars going to the fruit cluster come from these leaf sets.

Prune for blooms

However you grow your tomatoes, a little careful attention to pruning will make the results worth the effort.  Bigger and more bountiful harvests, larger fruit, and healthier plants are the benefits. 

Links and Resources

For more information about organic gardening, lifestyles, and living, visit our website at West Texas Organic Gardening.

If you found the information here helpful, you might also find these articles on our website of interest.

Tomatoes in West Texas

Tomato Propagation

Feed the Soil

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