When, Why & How to Prune Tomatoes
Pruning tomatoes? Aren't gardeners busy enough during the year, pruning roses and grapevines? Pruning tomato suckers is not a big, hairy project -- although it is fun to touch those hairy tomato stems and aromatic leaves. It's more like a once-a-week grooming of your tomato plants.
Rewards of Pruning Tomatoes
- Larger, earlier tomatoes -- a boon for those of us with short growing seasons (or cooler-than-usual summers).
- A slimmer plant that is easier to grow vertically.
- A healthier plant: growing tomatoes vertically increases air circulation between the leaves, and lifts the leaves and fruit away from crawling pests and dirt splashing on plants during rain
Two Schools of Thought on Pruning Methods
- Some suggest pinching the sucker off at its base, in the axil (or crotch) of the tomato plant, where the vertical stem meets the branch.
- UC Davis recommends "Missouri pruning", allowing two leaves to remain on the sucker and snipping off all the other sucker growth. The illustration shows Missouri pruning in action. The advantages of Missouri pruning are more photosynthesis, and more shade for the fruit (to keep sunscald at bay).
Pruning is for Indeterminate Tomatoes
As Tricia says in our video on tomato pruning and problem control, ONLY prune vining (indeterminate) tomatoes. The bush (determinate) tomatoes, like 'Roma', stop growing at a pre-determined height and should not be pruned.
START SNIPPING So, once a week, grab your snippers and get up close and personal with your vining tomato plants. See if that gives you a bigger, earlier tomato.
Pruning When Supporting Tomatoes on a String
If you have the set up and space, you can run a horizontal wire across your rows and ties string or twine on the top wire (must be very strong to support your heavy plants) at the position of each plant. Secure the string on the ground with a ground staple (or you can tie it loosely to the bottom of the plant) and you can wrap the plant around the string or tie it to the string. For this method of support it is advised to prune out all your suckers on the plant and only allow one leader to grow.
Using this method of support allows for the following:
- Planting tomatoes closer together
- Saves space by growing vertically and closer planting of plants
- Makes harvesting easier
- Better airflow around plants