Trimming tomato plants is optional, but it usually improves your harvest

You do not have to trim tomato plants to grow them successfully. Many gardeners plant tomatoes, water them, and harvest fruit without ever cutting a branch. But trimming — also called pruning or suckering — removes parts of the plant that do not produce fruit and redirects the plant's energy toward the tomatoes you want to pick. The result is usually larger fruit, better air circulation around the leaves, and easier harvesting.

Whether you trim depends on the type of tomato you grow and how much time you want to spend. Determinate varieties (bush types that grow to a set size and ripen all at once) rarely need trimming. Indeterminate varieties (vining types that grow taller and produce fruit all season) benefit most from it. If you have just a few plants and do not mind a wild tangle of branches, you can skip it. If you want bigger tomatoes or have limited space, trimming is worth learning.

Key Takeaways

  • Indeterminate tomatoes (vining types) benefit from trimming, while determinate tomatoes (bush types) usually do not need it.
  • Suckers are shoots that grow between the main stem and branches and produce leaves but no fruit; removing them redirects energy to fruit-bearing branches.
  • Trim in the morning when the plant is firm, use clean pruners or your fingers, and remove only one or two suckers per week to avoid shocking the plant.
  • Stop trimming four to six weeks before your first expected frost so the plant can focus on ripening existing fruit rather than growing new branches.

What suckers are and why they matter

A sucker is a shoot that grows in the angle between the main stem and a branch. It looks like a small branch sprouting from a branch. Suckers produce leaves but rarely produce flowers or fruit — they are the plant's way of growing more leaf area to capture sunlight, but they do not add to your harvest.

When you remove suckers, you force the plant to send its energy (water, nutrients, sugars) into the branches that do produce fruit. This means bigger tomatoes and more of them per branch. Removing suckers also opens up the plant's interior so air can flow through, which dries the leaves faster after rain and reduces fungal diseases like early blight and septoria leaf spot.

On a determinate (bush) tomato, suckers are less of a problem because the plant naturally stops growing at a certain height and puts most of its energy into ripening fruit all at once. On an indeterminate (vining) tomato, suckers can multiply quickly and turn your plant into a dense, tangled mass that is hard to harvest and prone to disease.

How to identify and remove suckers

Suckers grow at a narrow angle — usually 30 to 45 degrees — between the main stem and a branch. A true leaf branch grows at a wider angle, closer to 90 degrees. Once you spot a few, you will recognize them easily. They are usually smaller and thinner than the branches they grow from.

To remove a sucker, pinch it off with your fingers when it is small (2 to 4 inches long) or cut it with clean pruners if it has thickened. Pinching is faster and causes less damage. If you use pruners, wipe the blades with rubbing alcohol or a 10 percent bleach solution (one part bleach to nine parts water) between cuts to avoid spreading disease from plant to plant.

Remove only one or two suckers per week, even if you see more. Removing too many at once stresses the plant and can slow growth. Work in the morning when the plant is firm and turgid; a plant that is wilted from heat is more easily damaged.

When to start and stop trimming

Begin removing suckers when the plant is 12 to 18 inches tall and has several branches. If you start too early on a tiny seedling, you risk removing so much that the plant struggles to recover. If you wait until the plant is large and dense, you will have many more suckers to remove and the job becomes tedious.

Stop trimming four to six weeks before your first expected frost date in your area. At that point, the plant should focus on ripening the fruit already on the vine rather than growing new branches. Any new growth that appears after you stop trimming will not have time to produce ripe tomatoes before cold weather arrives.

If you live in a warm climate where frost does not arrive until late fall or winter, stop trimming in late summer when the plant is already tall and full. This prevents the plant from becoming an unmanageable giant.

Other trimming: removing leaves and lower branches

Beyond suckers, some gardeners remove leaves and branches for specific reasons. Removing the lowest leaves (those touching or near the soil) reduces disease because soil splashes fungal spores onto leaves during watering. Remove these leaves once the plant is at least 2 feet tall and has plenty of foliage higher up.

If your plant becomes very dense and the interior stays wet and shaded, removing some of the older, lower branches improves air flow. Do this gradually — remove one or two branches per week rather than stripping the plant bare. The leaves feed the plant, so removing too many at once weakens it.

Do not remove leaves or branches just before harvest or during heat stress. A plant that is already struggling from drought or extreme heat needs all its leaves to survive.

Determinate tomatoes: trim less or not at all

Determinate varieties grow to a fixed height (usually 3 to 4 feet), produce most of their flowers within a short window, and ripen most of their fruit at the same time. Because they are naturally compact and their growth is limited, they rarely benefit from aggressive suckering.

You can remove a few large suckers on a determinate plant if it becomes very dense, but most gardeners leave them alone. The plant's natural shape is already bushy and manageable. Focus your trimming effort on indeterminate varieties, which will grow 6 feet or taller and produce fruit continuously until frost.

Tools and hygiene

You do not need special equipment. Your fingers work fine for small suckers — just pinch them off. For thicker growth, use hand pruners (bypass pruners work better than anvil pruners for clean cuts). Pruning shears or a knife also work.

Clean your tool before you start and between plants if you are trimming multiple plants. Wipe the blade with a cloth soaked in rubbing alcohol, or dip it in a 10 percent bleach solution for 30 seconds, then rinse with water and dry. This takes 30 seconds and prevents you from spreading diseases like early blight or bacterial spot from one plant to another.

Frequently Asked Questions

Will trimming delay my harvest?

No. Trimming may delay the first flower by a few days, but it usually speeds up the overall harvest because the plant puts energy into fewer, larger fruit that ripen faster. You will pick more ripe tomatoes sooner than you would from an untrimmed plant.

Can I trim tomatoes in the afternoon or evening?

You can, but morning is better. Plants are firm and turgid in the morning after a night of absorbing water. In the afternoon, especially on a hot day, the plant is softer and more easily damaged by handling. Morning trimming also gives any small wounds time to dry before nightfall.

What if I accidentally remove a branch with flowers or fruit on it?

It happens. Pick the ripe or nearly ripe tomatoes off that branch and use them. If the fruit is still green, set it on a windowsill indoors to ripen, or use it for fried green tomatoes. The plant will recover and produce more flowers on other branches.

Do I need to trim cherry tomatoes?

Cherry tomato varieties vary. Some are determinate and compact; others are indeterminate and sprawling. Check the seed packet or plant label. If it says indeterminate, light trimming of suckers will help. If it says determinate, you can leave it alone. Either way, cherry tomatoes are prolific and will produce well with or without trimming.

What if my plant is already very tall and wild?

You can trim it, but do it gradually. Remove a few suckers and lower branches over one to two weeks rather than cutting it back hard all at once. A plant that loses too much foliage at once may stop growing and producing fruit for several weeks while it recovers.