How To Prune Tomato Plants for More Fruit

Prune tomato plants to direct more of the plant’s energy into fruit production and less into creating new foliage.

Growing tomatoes is one of the great joys of having a home garden. In a sunny spot, they deliver what seems like an endless bounty of fruit until the first frost.

Every summer, someone asks me, “Should I prune my tomatoes”? The answer is, as it many times is in gardening, “that all depends.”

If you have a determinate variety of tomatoes (bush-type – it will be listed on the plant tag or seed packet), then the answer to pruning is “no.” Let it grow wild and free. But if you have an indeterminate variety (a vine-type), then “yes”. If you’re not sure what kind you have, the tomato will clearly express its preference within 4 weeks of planting a seedling.

How to prune tomato plants

I was enlightened about pruning tomatoes when I read this section of Eliot Coleman‘s classic, The New Organic Grower: “Prune to a single stem and remove side shoots every few days…the fruit clusters should be pruned to three fruits on the first two clusters and four fruits thereafter.”

Mr. Coleman grows his tomatoes in a greenhouse and uses eight-foot overhead supports to train the vines upwards. If you can rig up overhead support, that’s just dandy, but the typical home gardener can get by just fine with a nice tall stake that stands at least 6 feet above the ground.

Train the tomato vine on a wooden stake

Tomato stakes should be driven aside the tomato seedlings right after they’re planted to avoid damaging the roots later. As the seedling begins to grow, train the tomato vine by gently tying it to the tomato stake with ribbon, old shoelaces, garden twine, or other soft material (do not use wire or bread ties, as they cut through the stems). You can also use tomato clips sold online, which are specially designed for this purpose. As the vine grows, tie it to the stake every 12 inches. Tying the vine to the stake keeps your line of sight clear for pruning and harvesting and can help the plant dry faster after watering or rainfall.

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Prune out suckers and secondary growth

The first time you prune tomato plants it might feel strange because you may feel you’re cutting off a lot of the plant. But this actually helps it produce larger tomatoes. Suckers, the growths in the crotches between the stems and shoot, should be pruned out as they appear (preferably when they’re small). You should also prune out all non-essential growth, like vines that are spilling out over the raised garden bed or becoming tangled with adjacent bushes. As the tomato vines grow taller than your tomato stakes, “cap” the vines (cut off the top), because by the time it reaches this point, any new tomatoes it produces most likely won’t ripen by your first frost.

Tomato cage or not?

In my experience, indeterminate tomatoes grow poorly in cages (although there are gardeners who would argue with me religiously about this). By the end of the season, the vines hang over the top of the cage and tend to become stressed under the weight of the fruit and the vines are prone to breaking. Tomato cages are great for determinate varieties, though.

Prune out the shoots closest to the ground

If you live in an area prone to wet summers, it’s wise to prune out the lowest shoots on all of your tomato plants. Leaves and shoots that touch the ground are prone to developing fungal infections like blight when rain splashes off the ground and carries fungal spores to the leaves. Keeping the lower 12 inches of the plant open allows the leaves to dry much faster after watering – tomatoes appreciate great airflow.

Speaking of which, don’t water your tomato plants overhead-style with a garden hose. If rainfall is insufficient, irrigate your tomatoes with a drip system or use a watering can around the roots only. Keeping the leaves as dry as possible will help keep tomato pests and diseases at bay.

See all of my posts with tips on growing tomatoes

More info: Tomato Pruning, Wisconsin Horticulture Division of Extension.