Pruning Tomato Plants: A Complete Guide for Beginners

Have you ever found yourself completely confused about how to prune your tomato plants? Well, you’re not alone! When I first started gardening, terms like “truss” and “sucker” left me scratching my head. I was terrified I’d prune the wrong part of the plant and end up with no tomatoes. But don’t worry, I’m here to help you make sense of it all.

So, what exactly are these “suckers” or “side-shoots” you need to pinch out? Well, let’s dive in!

Indeterminate vs. Determinate Tomatoes

First things first, there are two main types of tomato plants: indeterminate and determinate. Indeterminate tomatoes, also known as vine or cordon tomatoes, just keep growing and growing. In their natural habitat, they would spread along the ground. These are the ones we often train to grow tall using string or canes. And these plants keep producing tomatoes as long as the weather is warm and sunny. On the other hand, determinate, or bush tomatoes, grow to a certain height and then stop. Bush varieties tend to produce tomatoes in a glut, almost all at once. It makes them a great choice if you want to grow tomatoes for making sauce.

Why Pinch Out Side Shoots?

For indeterminate tomatoes, we pinch out side-shoots to help the plant focus its energy on producing and ripening fruit, rather than growing more foliage. This is especially important in places like the UK where we don’t get long, warm summers. By pinching out side-shoots, we ensure that the plant has enough sunny days to ripen its fruit.

For determinate tomatoes, you usually leave the side shoots on because the plant grows to a manageable size and produces most of its fruit at once. This makes them great for making sauces, as you get a big harvest all at once.

Spotting the Side-Shoots

Now, how do you actually recognize a side-shoot? Picture this: you have the main stem of your tomato plant, and leaves sprout off this stem usually at about 90 degrees to the stem. Right in the nook where a leaf meets the stem, a side-shoot can appear. If left unchecked, these side-shoots will grow into full stems.

Why bother?

Now you don’t have to prune your tomato plant, but there are a few good reasons why you might want to. Firstly, each stem that grows, produces masses of leaves and fruit. That’s a lot of work for the plant, so the more stems, the more energy that plant will use. Also, as brilliant as the idea of masses of tomatoes sounds, if you live in a colder climate like us, you might find that your plant grows lots of tomatoes but most of them never get to ripen, because the plant is spending all it’s energy producing more and more fruit. So here in Scotland, to help with this, we train our plants to one single-stem and restrict the growth of the plant to maybe 5 trusses of fruit. This helps to ensure that all those tomatoes have a chance to ripen.

How to prune out those side-shoots

Here’s what you do: simply pinch off these side shoots when they are small. If they get bigger, you might need to use snips. Don’t worry if you miss a few – just get them when you can. It really is that simple. Follow the main stem, identify the side shoots, and pinch or snip them off. Remember, only remove the shoots in the nook between the stem and the leaf – those are the ones stealing energy from your fruits.

I’m worried I’ll accidentally prune a fruiting truss

This was something that confused me when I was new to growing tomatoes and I know lots of you worry about this too. How to tell the difference between a side-shoot and a fruit truss. So here’s my simple tip.

Looking at the main stem again, we’ve already identified that the side-shoots appear in the crook between the leaf and the stem. Well, if you follow the stem up past the leaves, you can see the fruit truss there, coming out of the stem further up.

Bonus tip

Okay, confession time: sometimes I get busy and forget to pinch out the side-shoots. When that happens, the greenhouse turns into a jungle! But here’s a cool tip: you can actually turn these pruned side shoots into new tomato plants. Stick them in water or potting mix, and they’ll grow roots and become a whole new plant. It might look sad for a week or two, but be patient – they’ll perk up and voila, whole new plant.