A quick google search for “how to prune tomatoes” will yield pages upon pages of results from seed companies, garden content creators, extension offices and other organizations. It gets even more overwhelming because the advice seems to be contradictory from source to source.
So how do I have the BEST way to prune tomatoes?
I’ll let you in on a little secret…
The best way to do anything when it comes to gardening (& life) is to find what works for you. To grow your own way.
I know I lured you into reading this with promises of answering your tomato pruning questions and I will deliver on that promise, but first:
it doesn’t matter what everyone else is doing if it doesn’t work for you
When I decided that my garden was MY SPACE and I could do WHATEVER I WANTED there, I found a lot more success and I started enjoying the experience a lot more. Consider this your invitation to do whatever you want in the garden.
To Prune or Not to Prune
I’m assuming you’ve heard the metaphor - pruning parts of your life that don’t serve you anymore allows for more growth in other parts of your life. It might be cheesy, but it stands the test of time because it’s true. It’s true for tomatoes too.
Most of the context I see surrounding the pruning of tomatoes is through the lens of farming where there are concerns, like ease of harvesting, that don’t apply to backyard homesteaders or gardeners. Some of you may care about a 5% size difference in your fruit or growing an aesthetically pleasing shape, but I’m willing to bet that these are, again, primarily the concerns of commercial farmers.
Furthermore, most of the advice I see seems to disregard the context in which the tomato is grown. If you’ve been a reader for a while you should know that while I aim to provide accessible and actionable information, I’m not doing the work for you or giving you a magic bullet that blasts away all need for critical thinking. It’s the same here, there’s no single correct way to prune a tomato that can be applied to all plants in all situations. Plant density (how many plants in a square foot), variety of tomatoes, trellising system, and more are all factors that we need to consider.
The Facts:
Pruning is important for tomatoes to help:
reduces the risk of disease by increasing airflow around the plant and keeping leaves off the soil
increase yield by freeing up plant energy to be directed to fruit
manage and maintain vine growth to prevent plant breakage, keep walkways clear, and avoid damage to neighboring plants
promote efficient photosynthesis
help ripen fruit
Terminology:
Sucker: a "sucker" is a small shoot that grows in the axil, which is the space between the main stem and a branch or leaf stem of the tomato plant (see image above). These suckers can grow into full branches and produce fruit, but they also take energy away (i.e. suck energy) from the main plant, potentially reducing the overall yield and size of the tomatoes.
Leader: a "leader" refers to the primary main stem of the tomato plant. In the case of indeterminate tomato varieties, which continue to grow and produce fruit throughout the season, maintaining a single or a few main leaders can be beneficial for managing plant growth and fruit production.
When pruning, you can choose to maintain:
Single Leader: One main stem that grows vertically. This method is straightforward and ensures the plant's energy is concentrated on producing larger fruits along this single stem.
Double Leader: Two main stems are allowed to grow, typically by allowing one sucker near the base of the plant to develop into a second leader. This method can increase the number of fruits without overly complicating plant management.
To establish and maintain the desired number of leaders, prune off any additional suckers that develop along the main stem(s). This helps direct the plant's resources into the main leaders, resulting in a more manageable plant and better fruit quality.
Indeterminate: Indeterminate tomatoes are a type of tomato plant characterized by their continuous growth and production of fruit throughout the growing season. They are vine-like and have an extended harvest when compared to determinate varieties.
Determinate: Determinate tomatoes are a type of tomato plant that grows in a bush-like format. Once the plant start to produce fruit, overall growth slows down. Harvest periods are more condense, however they produce about the same amount of fruit as an indeterminate tomato in a season.
Plant Density: Plant Density refers to the number of plants in a given area.
Yield: Yield refers to the quantity of tomatoes produced.
Biomass: Biomass refers to the size or weight of the tomatoes produced.
The Best Way to Prune Tomatoes:
I read a few scientific articles on this topic since deciding to write this post. There’s evidence for pruning tomatoes to a single leader (removing all suckers). There’s evidence for pruning tomatoes to a double leader. There’s evidence for pruning tomatoes to four leaders. What this tells me is that the best way to prune a tomato is based on the context in which it is grown - plant density, trellis method, variety of tomato. Instead of pruning for yield, let’s prune for our gardens.
General Rule:
Prune indeterminate tomatoes to your trellising system. Prune determinate tomatoes for airflow.
Pruning to Your Trellising System
Indeterminate tomatoes are a vining plant, meaning they grow and grow and grow. If left alone they would bend over and grow along the ground. Most of the time we use a trellis to raise the tomato plant off the ground, which helps increase airflow, reduce disease, and allows us to plant more densely among other benefits. There are many different ways to trellis tomatoes and I have tried many of them. Single stake methods, Tomahooks or string trellises, Florida Weave, tomato cages, cattle panels.
Trellising systems and pruning go hand in hand. For example, if you’re using a single stake to support your tomato plants, you will prune your tomato to a single leader. That way the entire weight of the tomato plant can be secured to the stake. If you’re using a cattle panel you don’t need to prune as heavily because you have multiple places to secure the plant to the trellis. Pruning in this case is more dependent upon plant density, where you will prune leaves that are overlapping or touching neighboring plants.
Pruning for Airflow
Both indeterminate and determinate tomatoes benefit from improved airflow that results from pruning. This type of pruning focuses primarily on removing any leaves that are touching the ground.
If tomatoes are planted very close together, pruning for airflow also includes removing leaves that overlap or touch. Take that with a grain of salt because we are not about to be pruning every part of our plants that touch. This is where giving garden advice is tricky because I’m relying on you to apply your own discretion and tune into your own growing intuition. A general rule of thumb:
Are there ripening fruit present? Trim any leaves that are blocking the tomatoes from the sun.