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Growing Wisdom

How to prune tomatoes

If you are growing tomato plants itís important to keep them pruned for optimal health and fruit production. There are many different theories and practices on how to prune tomatoes. If you donít prune them, you will still get fruit, but the plants will become very weedy and sprawling.

There are two main categories of tomato plants, determinate and indeterminate. Determinate plants will reach about 4 to 5 feet and are typically sold as ďpatio tomatoesĒ. These types will eventually stop growing and mature earlier.

Indeterminate can grow to 10 feet, require more pruning and comprise the majority of tomatoes people grow in a home garden. I recommend pruning both types, but especially the indeterminate ones.


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The easiest pruning step is to remove the suckers in the crotch of the tomato vine. The image below shows the shoot coming out between two growing branches at about a 45 degree angle. You want to carefully remove these with your thumb and forefinger. You can also use pruning shears, but clean them between each plant so as not to spread disease.

tomato sucker in crotch.jpg

When staking tomatoes and they should be staked be sure to use ties that wonít cut the plant. Strips of old sheets works really well as do some of the other products like clips and Velcro. The latter should be reused so they donít get into the garden.

staking tomatoes.png

You want to train your tomato plants to grow up the support. I am using poles this year, but also use wire attached to a trellis. Itís also important to tie the plants in such a way as to support the fruit. The weight of the fruit can break the plant and I have lost tomatoes this way before they are fully ripe.

Watering tomatoes should be done early in the morning and using drip irrigation. Overhead water will promote disease and if the water droplets are present when itís sunny can burn the leaves.

I fertilize my tomatoes regularly during the season with a liquid fish emulsion. I also put granular tomato food into the soil at the beginning of the season and then again about 6 weeks after planting.

Lower leaves will naturally yellow over time, but if your entire plant is turning yellow you likely have some disease. Early blight is one of the most common tomato diseases.
At the end of the season about 30 days before the first frost, top your plants. Itís can be psychologically hard to cut the top of the plant off after nurturing it all summer, however, this will encourage the fruit to ripen and not be left to rot on the vine or on a window sill in your kitchen.

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