Between their many varieties and two very different growing habits, pruning tomatoes can seem complicated. In fact, it's straightforward as long as you know which type of tomato you're growing. This guide covers how to prune tomatoes of each type, how to avoid common mistakes, and when to prune tomatoes.
While this advice breaks down tomato pruning into basic principles and easy-to-follow steps, know that there is room for experimentation and even error. You can still grow a generous harvest of tomatoes even with a few pruning missteps.
Skip Ahead: How to prune tomatoes • When to prune • Determinate varieties • Indeterminate varieties • Tomato pruning mistakes • Tomato pruning diagram • FAQ
How to prune tomato plants
Before pruning tomatoes, it's important to know which type you're growing: determinate or indeterminate. Determinate tomatoes have a bushy growing habit and indeterminate tomatoes are vining plants, so they have different pruning requirements. This applies regardless of which variety of tomato you're growing; cherry tomatoes, slicing tomatoes, and paste tomatoes are all available in both vining and bushing forms.
In terms of pruning, the major difference between determinate and indeterminate tomatoes is that indeterminate tomatoes need regular pruning, while determinate tomatoes only need pruned once at the beginning of the season. Here are the basics:
- For either type of tomato, pinch off any suckers growing below the first set of flowers. If your tomatoes are determinate types, that's all you need to do.
- For indeterminate tomatoes, you'll want to check back regularly to trim off any new suckers that appear throughout the season. This makes vining tomatoes much easier to grow up a stake or along a trellis.
- Pinch the tops off of indeterminate tomatoes once they've produced three to five sets of flowers or fruit. This is not necessary for determinate varieties.
- Trim off leaves that shade out the fruits only at the very end of the season, when the tomatoes are running out of time to ripen.
That's a general overview-- read on for the hows and whys of pruning determinate and indeterminate varieties.
Read More: How to Grow and Harvest Tomatoes
When to prune tomatoes
The best time to prune tomatoes is once they have produced their first set of flowers. At this point, prune any suckers growing below those flowers. For indeterminate tomatoes, it's also necessary to prune any unwanted suckers growing above those flowers.
The best time of day to prune tomatoes is in the early morning or evening. This will prevent moisture loss and give the plant a chance to recover somewhat before temperatures rise again around midday.
Pruning determinate tomatoes
Determinate tomatoes are the easiest type to prune, whether they're cherry tomatoes, paste tomatoes, or beefsteak varieties. This is because determinate varieties (also called bush tomatoes) have been bred to be compact; ideal for growing tomatoes in pots and small spaces.
Whereas indeterminate tomatoes grow tall and sprawl across the ground if allowed, determinate tomatoes reach a predetermined size and height. All that's needed here is a little maintenance. Here's how to prune determinate tomatoes in early summer:
- Wait to trim bush tomatoes until the first set of flowers appears.
- Pinch or cut off any suckers growing below the first flowers. Don't prune above the first flowers.
- Prune any dying branches that are touching the soil, as these can invite disease.
- Trim off underdeveloped fruit, flowers, and unnecessary branches at the very end of the season-- one or two weeks before the first frost. This will give you the best chance of being able to harvest any unripe tomatoes still on the vine.
That's all there is to it; minimal pruning involved. With determinate tomatoes, you don't need to pinch out the top or regularly prune out suckers.
The reason for this is that any additional suckers that grow on determinate tomatoes above that first set of flowers that will go on to produce their own flowers and fruit. Pruning determinate tomatoes above the first flowers will only eliminate potential future fruit; you could easily prune a sucker or branch that would've otherwise gone on to flower.
Pruning indeterminate tomatoes
Indeterminate tomatoes have no predetermined height or size, and they are vining plants; without pruning, indeterminate tomatoes will quickly sprawl and become completely unmanageable. For the gardener, this inevitably means fruit growing close to or against the ground on heavy branches, ripe fruit going unnoticed and falling off the vine, and a lack of light and airflow that makes ripening more difficult and invites disease.
Pruning indeterminate varieties can be a bit of an art, but the basics are straightforward. Here's how to prune indeterminate tomato plants for maximum yield:
- Trim off any suckers below the first set of flowers.
- Prune new suckers as they appear throughout the season.
- Pinch off the tip of the plant once it has reached your desired height-- typically once it has set three to five tresses of flowers or fruit. Indeterminate tomatoes will continue growing taller right up until the frost; this will stop that growth and encourage the plant to put more energy into developing fruits.
- Prune non-fruiting branches and any leaves that shade out fruit at the very end of the season, if you still have fruit that needs to ripen. This will give them a better chance at ripening before the first frost kills the plant.
Unlike determinate tomatoes, whose suckers grow to a manageable size, indeterminate tomatoes' suckers will grow with as much vigor as the rest of the plant-- and will produce their own suckers, all of which will do the same.
A simple solution is to prune every single sucker on the plant, and regularly. A vining tomato pruned this way would be left with one single leader stem that had sun leaves and flowers branching off of it-- much easier to trellis or train up a stake.
Here's where the art comes in: if you have more space, you may want to leave one or two suckers on the plant to grow into additional leader stems. These will produce more fruit-- three to five tresses each, typically-- but they'll also take up more space and require more pruning as the season goes on.
Think of each sucker as an additional leader; a plant with a leader and a sucker branch will require as much pruning as two plants pruned down to one main leader each. A tomato plant with two suckers and a main leader will require three times as much pruning attention as it would with just a single leader. This might not be a concern if you're only growing one or two tomato plants. If you're growing a row of tomatoes for canning, it may be best to keep it simple and prune each plant down to one leader.
When it comes to pruning down to one leader or leaving a few, there is no right answer. Either approach will provide a mass of delicious fruits. How you prune your tomatoes comes down to how you want to manage your garden, and what works with your space and schedule.
Tomato pruning mistakes
The task of pruning tomatoes is often overcomplicated and can become quite intimidating. The truth is, tomatoes want to produce fruits. Most gardeners find the plants more enjoyable to grow when they're pruned and trained, but you're unlikely to decimate your tomato harvest or irrevocably damage a plant through pruning mistakes-- with one or two exceptions.
Here are a few common tomato pruning mistakes that you can easily avoid:
- Waiting too long to prune. Tomato plants can grow very quickly, so it's worth keeping an eye out for that first set of flowers. Otherwise, the plant can pour a lot of energy into developing sturdy suckers that will just end up being pruned off.
- Pruning too much at once. Indeterminate tomatoes can benefit from aggressive pruning, but trimming too many branches in one go can stunt the plant. Aim to prune a little bit regularly, ideally trimming off no more than a third of the plant at a time.
- Not pruning indeterminate tomatoes. It may be a rite of gardening passage to let vining tomatoes go unpruned and celebrate the initial burst of healthy growth, only to give up on the unmanageable plants halfway through the summer and lose most of the harvest. You will most assuredly get more tomatoes from a plant with one or two leader stems than you will from a plant allowed to run rampant-- but you're welcome to try any approach you like.
- Pruning sun leaves. Not to be confused with suckers, which grow at a 45º angle from the leader, sun leaves grow at a 90º angle from the leader and have the sole purpose of feeding the plant. Both above and below the first set of flowers, they should be left alone.
- Not pinching off indeterminate tomatoes. Indeterminate tomatoes will grow vertically right up until the first frost kills them, but this isn't ideal for fruit production. Instead, pinch the tops off of indeterminate tomatoes once they have set three to five tresses of fruits or flowers; this is the most we can reasonably expect a plant to produce and ripen, especially in northerly zones. Pinching out the top will ensure that the plant's energy goes where it's needed most.
- Pruning in midday. Pruning is best done in the early morning or evening, when temperatures are cool. Plants pruned in the midday heat will suffer unnecessary water loss.
Tomato pruning diagram
When pruning tomatoes, the main things to identify are suckers and the main leader stem. Here's what those look like:
When should I prune tomatoes?
The best time to prune tomatoes is after they are planted out, once they have produced their first set of flowers. At this point, prune off all suckers below the first flowers. On indeterminate tomatoes, prune any suckers above the first set of flowers, as well. If you aren't sure whether a branch is the main leader or a sucker, let the plant grow on a bit before pruning.
What are tomato suckers?
Tomato suckers are branches that grow at a 45º angle between the leader stem and other branches. If allowed to grow, they produce flowers, sun leaves, and more suckers. Suckers should be pruned off below the first set of flowers on all tomatoes. On indeterminate tomatoes, they should also be pruned off above the first set of flowers throughout the season as the plant grows.