You prune tomatoes based on which type you grow. Determinate types should never be cut back at all. Indeterminate types grow better when you remove side shoots. This pushes energy into bigger fruit instead of extra leaves.
In my experience, pruning makes a huge difference on the right plants. I grew two Cherokee Purple plants side by side last summer to test this. I pruned one down to three main stems and left the other to grow wild. The pruned plant gave me tomatoes that weighed 20-30% more per fruit. They also ripened about a week sooner than the unpruned plant's fruit.
The science behind pruning is simple. Suckers are small shoots that pop up in the joint between a main stem and a leaf branch. Each sucker turns into a full new vine that needs water, food, and light. Removing tomato suckers sends all that energy into fewer fruit. The result is bigger tomatoes that ripen faster on a plant that's easier to manage.
But here's the critical rule. Never prune determinate plants. These compact types grow only 24-30 inches tall and set all their fruit at once on existing branches. Cut off a branch and you cut off future fruit. Determinate types handle their own growth and don't need your help at all.
Indeterminate plants grow 3-5 feet or taller and keep producing fruit all season long. These are the ones that need pruning to stay under control. Without it, they turn into a thick bush that blocks air flow and invites fungal disease. Good pruning opens up the plant so sun and wind reach every branch.
This tomato pruning guide walks you through the steps. Start when to prune tomato plants is easy to spot. Look for suckers once your plant reaches 12-18 inches tall and check every week after that through the whole growing season.
Find the Sucker
- Location: Look in the V-shaped joint where a leaf branch meets the main stem of your tomato plant.
- Size check: Small suckers under 2 inches are easy to pinch off with your thumb and finger right away.
- Timing: Check your plants once a week in the morning when stems snap clean and heal fast in the sun.
Remove Small Suckers
- Pinch method: Grab the small sucker between your thumb and finger and bend it back and forth until it snaps clean.
- Clean break: A quick pinch leaves a small wound that dries and seals within hours on a sunny day.
- No tools needed: Suckers under 2 inches don't need scissors or pruners since fingers work better for a clean removal.
Cut Large Suckers
- Use clean tools: Grab scissors or pruners wiped down with rubbing alcohol to stop disease from spreading between cuts.
- Cut close: Trim the sucker off close to the main stem but leave a tiny stub so you don't damage the branch joint.
- Limit cuts: Only remove 2-3 suckers per session so the plant doesn't go into shock from losing too much at once.
Keep 2-3 main stems on each plant and remove all other suckers as they show up. This gives you a strong open frame that holds plenty of fruit. Learning to prune tomatoes the right way takes one season of practice. After that it becomes second nature and your harvests will show the difference in both size and flavor.
Read the full article: Growing Tomatoes: Beginner-Friendly Guide
