If you’re looking for a simple guide for pruning tomato plants, you are in the right place. Tomatoes are one of the most popular GIY (grow it yourself) veggies out there. And for good reason! Everybody knows that store-bought tomatoes can’t hold a candle to the ones you can get fresh off the vine in your backyard. You may have bought tomato plants every year, thrilled with your harvest. But what if I told you that your plant was holding out on you?
Indeterminate vs. Determinate Tomato Plants
A note before we go any further: the following pruning advice applies only to “indeterminate” varieties. Unlike “determinates,” which produce their fruit all at once and then are done for the season, indeterminate tomato varieties provide a steady stream of tomatoes, one bunch at a time.
Whereas determinates are ideal for large-scale canning operations, indeterminates allow you to snack all summer long. Now that you know the difference, let’s look at the four types of tomato plant growth to learn what you should be pruning and what you should be keeping.
The Four Types of Tomato Plant Growth
There are four main types of growth you will see on your tomato plants. You need to be careful to prune the right parts and leave the essential parts of the plant.
Main Stalk
The main stalk, also known as the “leader,” is pretty easy to identify at any stage of plant growth; it is the part of the plant coming directly out of the ground. You likely won’t be tempted to cut this stem unless you’re unsure if the leader is a sucker. More on this later.
Leafing Branches
The leafing branches are also easy to spot. These branches come directly out of the main stalk and do the essential work of converting sunlight into energy for the plant to grow.
Fruiting Branches
Fruiting branches are self-explanatory: the actual tomatoes will grow out of these branches! These branches also come from the main stalk but are thinner than leafing branches. Small yellow flowers on the branches indicate where the tomatoes will pop out.
Suckers
Suckers are the main part of the tomato plant you will be pruning. They can also blend in if you don’t know what to look for. Emerging in between a leafing branch and the main stalk, suckers are an attempt to grow a new tomato plant.
3 Reasons To Prune Your Tomato Plants
The two types of plant growth you will need to prune are the lower-leafing branches and the suckers. Let’s start with the lower-leafing branches.
Lower Leafing Branches
Leaves perform the act of photosynthesis that brings energy to a tomato plant and helps it to grow. When you cut off the lowest leafing branches, the tomato plant receives a signal to grow. When the plant grows, it is able to create more leafing branches that will bring the plant energy.
A rule of thumb is to prune the leafing branches only up to the branch with fruit on it. Once you harvest the tomato from a branch, the plant will produce no more tomatoes from that same branch. At this point, you can prune the leafing branches above it until you reach the next fruiting branch.
Prune to Avoid Disease and Pest Pressure
Pruning lower-leafing branches not only stimulates plant growth, it also keeps the plant healthier. You never want leaves to touch the soil since that is where bacteria and fungi will be introduced to your plant. Even low-hanging leaves are susceptible to fungal disease. When rain falls on the soil below the tomato plant, water will absorb fungi in the soil and splash upwards, coming into contact with low-hanging branches.
When a part of a tomato plant, even a single leaf, is diseased, it is essential to cut it off quickly. Most likely, any leaf that is touching the ground for very long will become diseased. You can tell that it is diseased by its color–the leaf will start turning brown. Cut these off before the disease is allowed to spread to the rest of the plant.
Another reason to remove diseased lower leaves is that they will attract pests that will begin to eat away at both the diseased and the healthy parts of your plant. A leaf touching the ground is an insect onramp.
Pruning Suckers To Maximize Tomato Plant Fruit Production
As mentioned above, suckers are the tomato plant’s attempt to create another tomato plant. Why is this a bad thing? Creating a new tomato plant takes a lot of energy–energy that could otherwise be used to produce more fruit on the original plant! It may feel exciting to see the plant growing so much, but, as is the case with leafing branches, you have to ask yourself, ‘Do I want to grow more leaves or more tomatoes?’
When you prune the suckers off your tomato plants with regularity, you are keeping the plant contained and away from its neighbors. In the garden bed where we’re growing our tomato plants this year, we were able to fit 8 plants in a nearly 10-square-foot growing space. They are definitely tight, but, because we’ve pruned them so intensely, they are able to grow side by side without blocking sun or airflow for any of our tomato plants.
A Warning About Pruning Suckers
The part of the plant you need to avoid pruning the most is the main stalk. While the main stalk seems easy to identify, it can become unclear as you reach the top of the plant. You will always want to take care to distinguish between a sucker and the “leader.”
The leader comes out of the top of the plant, but sometimes a sucker will appear right next door! When in doubt, wait for the plant to grow a bit more so you can tell between the two. The sucker is more likely to grow to the side, whereas the leader will grow straight up.
If you accidentally remove the leader, you can continue plant growth by keeping a sucker and treating it as the new leader.
Bonus: Prune Anything that is Diseased, Dying, or Dead
As harsh as it may feel, the best thing you can do for your tomato plant is to remove any part of it that is diseased, dying, or dead. If you see a branch that is a different color than the others, cut it off and let the plant focus its energy on the healthy parts. If you leave the dead branch, the tomato plant will expend excessive energy in an attempt to save it. In our experience, it’s best to cut your losses for future gains.
If you are growing many tomato plants—more than 10—you will want to be sure to cut out and remove entire diseased tomato plants so as to avoid spreading the disease to neighboring plants. These plants have a very small chance of recovery, and it is not worth risking your other tomato plants to keep one alive.
We hope you feel empowered to prune your tomato plants with confidence. Pruning will bring you beautiful plants and, more importantly, abundant amounts of tomatoes. Happy pruning!
