How to Prune Tomato Plants

Determinate vs. indeterminate: the whole game

Determinate varieties grow to a fixed size, set flowers at nearly every branch tip at once, ripen a concentrated crop, and stop. Because the branch tips are the crop, pruning or topping them removes yield directly — at most, remove the few suckers below the first flower cluster to lift the plant off the soil, and leave everything above alone.

Indeterminate varieties keep extending and flowering until frost. They don't strictly need pruning, but unpruned plants become a sprawling thicket; pruned to one or two stems on a stake or string, they ripen earlier, produce larger fruit, and dry out faster after rain, which reduces fungal disease.

Check the tag or packet: 'DET'/'bush' means hands mostly off; 'INDET'/'vining' means prune to your training system.

How to remove suckers (indeterminate plants)

Snap suckers off by hand when they are small — a few inches long — bending them sideways until they pop off cleanly; use clean pruners only on thick, missed ones. Work weekly, and preferably on a dry day so wounds seal fast.

Single-stem training: remove every sucker along the main stem, all season, and tie the leader to its stake or twine as it climbs. Two-stem training (UNH's version): keep the sucker just below the first flower cluster as the second leader and remove all others — this trades a little earliness for more total fruit and more leaf cover.

Minimal pruning is legitimate too: caged indeterminate plants can be left mostly alone, with just the lowest leaves and suckers removed for airflow at the base. More stems = more but smaller fruit, later; fewer stems = fewer but larger fruit, earlier.

Two cautions: sunscald and late-season topping

Leaves are sunscreen. Iowa State warns that when excessive pruning removes too much foliage, fruit exposed to bright sun develops sunscald — pale, papery patches that ruin the tomato. Prune for airflow, not for bare stems, and never strip leaves directly shading fruit clusters in high summer.

Near season's end, you can top indeterminate plants — cut the growing tip of each leader — so the plant stops making new growth and puts its energy into ripening the fruit already set. UNH also describes topping any time plants outgrow their support to keep them manageable.

Do not top determinate varieties at any stage — same logic as sucker removal: you'd be cutting off the crop.

Sources

Reviewed 2026-07-18. We cite university Extension, government, and established horticultural sources — and never invent pesticide rates or dangerous treatments.

• University of New Hampshire Extension — Pruning Tomato Plants (fact sheet) — Suckers are new shoots that develop in the leaf axils; one leader is most commonly recommended for trellised plants, and for two leaders keep the sucker just below the first flower cluster and remove all others; pruning can improve harvestable yields, prolong harvest, reduce fungal disease by keeping plants off the ground, and improve fruit quality; tops can be removed when plants exceed their support or to push late-season ripening.
• Iowa State University Extension — Pruning Tomatoes in the Home Garden — For determinate tomatoes remove suckers only up to the first flower cluster — there is no need to remove suckers above that point and yields do not increase by doing so; for indeterminate tomatoes suckers can be removed as they form all season; removing too much foliage exposes fruit to sunscald.

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