How (and Why) to Prune Tomato Plants
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As a gardener who loves to keep things simple, I used to wonder, “Do I really need to prune our tomato plants?” I mean, even a messy garden with weeds and overgrown plants still seems to produce. But the truth of the matter is that there are good reasons for pruning tomato plants a few times each season.
Pruning your tomato plants can leader to healthier plants, more fruit, and a bigger harvest. All of which means more tomatoes that you might not otherwise get from your garden. And more tomatoes is always a good thing in my book – just think of all of the sauce, salsa, and snacks you’ll provide!
If you often struggle with diseased tomato plants, if your tomato plants droop over or look “sick,” or if you are often left with green tomatoes at the end of the season, pruning is something you should add to your to-do list.
In short, the answer is “YES, you should prune your tomatoes” – if you want the best results possible from your garden. Read on to learn why it matters, and how to do it!
Hint: The same is true for basil – pruning leads to awesome harvests!
There are 3 main reasons for pruning tomato plants, and they all have to do with producing a more plentiful and healthier tomato harvest.
First, tomato leaves and branches that reach down and land on the ground (the ones you often see turning yellow) can be a great host for diseases or bugs just waiting to hitch a ride. By trimming these low-hanging off-shoots you can make it harder for those diseases to spread.
Second, plant diseases also spread more readily in a tomato plant that is thick with foliage all clumped together. By pruning your tomato plant, you create air circulation, thus helping the breeze to blow through and making it harder for diseases to spread from leaf to leaf. You also lighten the load a bit, meaning your plant will have less weight and may not droop over as badly.
Third, as the end of the season gets closer you will want your plant to focus more on growing fruit than on growing leaves. By starting to trim new growth at the top of the tomato plant, you will signal your plant to stop producing greenery and encourage fruit to ripen. Basically, you’re telling the plant it can stop growing taller and start making those tomatoes fatter.
When do you Prune Tomato Plants?
You don’t want to immediately start pruning your tomato plants because you’ll challenge the plant too much when it is first getting going. Wait until about 1/3 to 1/2 of the way through the season, and look for low-hanging branches that are starting to turn yellow. When this happens, it’s a good sign that your plant is ready for pruning.
You’ll also know that it is time to prune when the plant starts to look really full and crowded in your support cage or hanging off of your stake (read more about stakes and cage options here).
At the end of the season, you can start pruning when nights are getting cold and you anticipate that your first frost will come in 2-3 weeks. By pruning the top of the plant at this time of the season, you’ll give the existing fruit just enough time to ripen before the cold weather sets in. 
How do you Prune Tomato Plants?
To prune tomatoes, you’ll need a nice sharp pair of pruning shears; we love our Fiskar’s Pruning Shears for so many uses in the garden – a good pair of shears is always a good investment.
There are a couple of things to look for when pruning tomato plants:
1. The first thing you’ll look for is branches that have leaves but no fruit and are starting to turn yellow or brown or show other signs of disease. Often, these branches are brushing or even laying on the ground. These are the ones that can convey diseases. Clip them as close to the main stem as possible and compost them far away from your tomatoes.
2. To clear space in your plant and allow air to circulate, you can also trim branches that are higher up on the plant and are not producing fruit. Often, you’ll see two branches coming out from your tomato – one with fruit and then one below it that points down and has just leaves. These lower branches are good candidates for trimming when your plant has gotten too crowded. Clip these close to the main stem. Don’t take all of these branches away, as that can make your plant panic and put energy into greenery, but trim about 1/3 to 1/2 of them to allow your plant some breathing room.
3. Look for “suckers” which are branches that shoot up from the ground around the main stem. These suckers can take energy away from the main plant, so you’ll want to eliminate the competition by cutting them as low as you can go on the base.
4. At the end of the season, look for green branches pointing straight up that are relatively new. Keep these at bay to let the plant know that you don’t need any more vertical height.
More Information on Growing Tomatoes
Tomatoes are one of the key vegetables that we grow in our garden; we use so many tomatoes for sauce, salsa, and just plan snacking. This crop is hands down our biggest return on investment. Here are some more helpful resources on growing and using tomatoes at your homestead!
- How to Plant a Tomato Seedling
- How to Support Tomatoes: Stakes vs Cages
- How to Make Tomato Sauce in an Instant Pot
