Want better tomatoes? Learn to prune them. Done right, pruning and staking give you larger fruit sooner, plants that dry off faster after rain, and a tomato bed you can actually work in. A pruned and staked plant produces larger fruit two to three weeks earlier than one left sprawling on the ground.
One thing worth knowing before you grab the pruners: pruning is a choice between more, smaller tomatoes and fewer, larger ones. In general, more stems means more but smaller fruits, produced increasingly later in the season. Fewer stems means fewer but larger fruit. This guide walks you through those choices.
The right tool helps. The Felco #2 pruner has been in our hands for more than 40 years.
Related: Learn why in our article on the Felco F-2 Classic Manual Hand Pruner
First, Know Which Type Of Tomato You Have
Pruning rules depend on whether your tomato is determinate or indeterminate, so check the plant tag or seed packet before you cut anything.
Determinate tomatoes have a bush habit. University of New Hampshire Extension says they stop growing once they set a terminal bud, usually around 4 feet tall, and give a short, defined harvest season. (NC State Extension puts them at about 3 feet.) Indeterminate tomatoes keep growing until frost and keep setting flowers and fruit the whole time. UF/IFAS says they may reach 10 feet or more if conditions are perfect.
Go easy on determinate tomatoes. The Connecticut Agricultural Experiment Station says they need no pruning other than removing all suckers below the first flower cluster, and that any pruning above that cluster throws away potential fruit. Iowa State University Extension agrees: yields do not increase by removing suckers beyond the first flower cluster.
Indeterminate tomatoes are the ones to prune. Keep removing suckers as they form, all along the main stem, throughout the growing season.
Get Support In Place From The Start
Indeterminate plants get tall and heavy, so put your support in when you plant. Stake tomatoes to keep the fruit off the ground, then tie the plants to the stakes at a few different heights just below the fruit clusters. Stakes, a high trellis, or twine woven between stakes all work. Clemson Extension calls the twine method the Florida weave.
A well-supported plant is also easier to read. You can see the main stem, the fruit clusters and the suckers, so you can plan each cut instead of guessing.
Related Reading: Epsom Salt For Tomatoes: What It Actually Does (and When to Use It)
Related Reading: Tomato Growing Dos & Don’ts
What About Tomato Cages?
You won’t want to use tomato cages like these for tall indeterminate plants, because the cages tend to hold all of the limbs together. That makes it hard to see which shoots need pruning and which should stay.
The extension guides back up the general point. Ready-made tomato cages are too small for all but the smallest determinate varieties, and even large cages may not be enough for an indeterminate tomato you don’t prune. Cages do work well for plants with three to five stems, and are especially useful for determinate types. Caged plants are usually pruned just once, to three or four main stems.
What Pruning Does (and What It Doesn’t)
Pruning changes where the plant puts its energy. It helps plants direct more energy to flowering and fruiting. Extension sources describe suckers a little differently. Some call them mostly leafy growth that produces little, if any, fruit; others say a sucker left alone grows just like the main stem and produces flowers and fruit. Extra stems also divert some of the plant’s sugar production from fruit to extra growing tips.
Pruning and support also help with disease. The leaves of a pruned and supported plant dry off faster, so bacterial and fungal pathogens have less opportunity to spread, and upright plants have fewer problems with leaf spots and fruit rots. Removing suckers can also open the canopy for better air circulation. That can mean fewer fungal diseases to worry about.
It saves space, too. Left alone, a vigorous indeterminate plant can easily cover a 4- by 4-foot area with as many as 10 stems. For staked plants, allow 18 inches for a single stem, 24 inches for two stems, and 36 inches for three or four stems.
Related: Learn more about How Far Apart to Space Tomatoes.
Does pruning mean a bigger harvest? Not guaranteed. Removing and pruning tomato shoots can promote more flower growth, resulting in greater fruit production, and pruning can improve harvestable yields and prolong the harvest season. But removing suckers also reduces potential yields while increasing airflow, and more stems means more but smaller fruit. Think of pruning as a trade: larger, earlier fruit and healthier plants, with the total count depending on how many stems you keep.
Don’t overdo it. You don’t need to remove every sucker, especially if it leaves the leaf canopy very open, because exposed tomatoes can get sunburn or sunscald. Also avoid removing more than one-third of the plant’s foliage at a time, and leave the leaves that shade the fruit.
How To Prune Indeterminate Tomatoes, Step By Step
- Start with clean, sharp tools. Disinfect your hands and pruning equipment and clean them between plants, or every few plants, to help prevent spreading disease. These are our favorite pruners.
- Prune when the leaves are dry. Avoid pruning or tying plants when the leaves are wet, and prune on a dry day.
- Find the sucker. Follow the main stem up to a spot where a compound leaf joins it. The new stem growing in between is the sucker.
- Pinch it off while it is small. Advice ranges from under 2 inches to no more than 2 to 4 inches, or simply less than a few inches. Snap it off with your fingers. A stump left by a knife or scissors can easily become infected, and once a sucker is too tough to snap, you need a blade. Cut cleanly and don’t leave a jagged wound.
- Keep the space below the first flower cluster free of side stems. That is best.
- Choose how many main stems to keep. Advice varies: two to three main stems, one or two (or three or four for caged plants), or anywhere from one to as many as four on indeterminate tomatoes. Pick a number, then remove the other suckers as they appear.
- Protect the growing tip. Avoid the top 10 inches of the stem when removing suckers so you don’t take off the growing tip.
- Leave the leaves that shade the fruit. Newly exposed tomatoes can often suffer sun scald.
Snapped-off suckers don’t have to go in the compost. This short video shows how to root them into new plants.
Missouri Pruning: A Gentler Option For Big Suckers
If a sucker gets away from you, try Missouri pruning. You pinch out just the tip of the sucker and let one or two leaves remain. The upside is more leaf area for photosynthesis and better protection for the developing fruit from sunscald. The downside is that new suckers inevitably develop along those side stems, which means more pruning later.
This is the better move when suckers are already large. Removing just the tip is less of a shock to the plant than removing a foot or so of side stem, and if disease hits, it is farther from the main stem.
Keep The Bottom Of The Plant Clean
The lower leaves are the ones that get splashed. Remove the leaves and side shoots from the bottom 6 to 12 inches of the plant, especially anything that touches or comes close to the soil. This keeps soil-borne diseases from splashing up when raindrops hit the ground, and adding mulch around the base reduces soil splash further. That helps against soil-borne problems such as early blight and Septoria leaf spot. Learn more in our guide to tomato blight.
Top Your Plants Late In The Season
Near the end of the season, topping helps the fruit you already have ripen. By removing the growing tip of the main stem, the plant directs more energy into maturing the existing fruit instead of making new leaves, flowers and stems. It is best done about four to six weeks before your average first fall frost date. Cut the main stem just above a leaf or a fruit cluster, in dry weather.
Timing matters. Topping too early can reduce overall plant growth and yields, and topping determinate tomatoes at any stage will significantly reduce their yields. You can also remove flowers as they appear, starting about four weeks before the first fall frost, to help late-season ripening.
Final Thoughts
Pruning tomatoes is a set of choices. One or two stems for larger fruit, or more stems for more, smaller ones. Leave determinate types mostly alone, and prune indeterminate types early and often, while the suckers are still small.
Skipping pruning altogether is one of the tomato-growing mistakes we cover in another guide, and our high-yield tomato guide takes in the rest of the growing season.
Related: our guide to natural tomato fertilizers.
How many stems are you growing this year, one or two? Tell us in the comments.
Frequently Asked Questions
Should you prune determinate tomatoes?
Only a little. Determinate tomatoes need no pruning other than removing all suckers below the first flower cluster, and pruning above it throws away potential fruit. Yields do not increase by removing suckers beyond that cluster. Save your serious pruning for indeterminate varieties.
When should you remove tomato suckers?
While they are small. Advice ranges from under 2 inches to no more than 2 to 4 inches. Snap them off with your fingers, because a stump left by a knife or scissors can easily become infected. Prune when the leaves are dry.
Will pruning give you more tomatoes?
Not always. Pruning and staking together tend to give larger fruit sooner. A pruned and staked plant produces larger fruit two to three weeks earlier than one left on the ground, and fewer stems means fewer but larger fruit. Pruning can also improve harvestable yields, so expect a trade between size and count.
How many stems should you leave on a tomato plant?
It depends on your method. Advice varies: two to three main stems on indeterminate tomatoes, or one or two, or three or four for plants in wire cages. Indeterminate tomatoes can have one to four stems, and fewer stems means fewer but larger fruit. Pick a number and prune to it.
When should you top tomato plants?
Late in the season. Topping indeterminate plants is best done about four to six weeks before your average first fall frost date, and doing it too early can reduce overall plant growth and yields. Skip topping determinate types, which will significantly reduce their yields.