Tomato plant pruning is a hotly debated topic among gardeners. In this article we will reveal when you should pinch out your tomatoes and how to prune a tomato plant correctly.
Rarely does a topic divide tomato lovers as much as the pruning of tomato side shoots. Some argue for consistent tomato pruning, always and with every plant, whereas others simply let their tomatoes grow wild. In this article, we would like to show you that tomato pruning is not just a matter of opinion but has real advantages and disadvantages. We will explain how and why to prune tomatoes and give step-by-step instructions for trimming tomato plants.
- Is pruning tomatoes necessary?
- Advantages of pruning tomatoes
- Disadvantages of trimming tomatoes
- How to trim tomato plants: tomato pruning guide
- Pruning different tomato plant varieties
Is pruning tomatoes necessary?
Do tomato plants actually need to be pruned? In short, whether or not to prune a tomato plant depends on the variety, the location and the space available. Here is our in-depth guide on which tomato plants to pinch out and why.
Do all tomatoes have to be pinched out?
The simple answer is no. With large-fruited tomato varieties such as ox-heart and beef tomatoes, however, the side shoots should be removed. Even with medium-sized indeterminate tomatoes, we recommend only leaving a maximum of two to three shoots, including the main shoot.
Which tomatoes should not be pruned?
Determinate growing bush tomatoes or wild tomatoes do not require any pruning. They bear flowers on all side shoots, and so bear fruit again. Highest yields are achieved without trimming. With small-fruited cocktail and cherry tomatoes, you have the option of either letting the tomato plant grow bushy or pruning to leave just a few shoots.
How many side shoots to leave on the tomato plant?
Wild tomatoes from South America grow and spread out naturally from all leaf axils, growing low to the ground and forming a densely branched bush over time. Our domesticated tomato (Solanum lycopersicum) was cultivated from these diverse wild tomatoes (Solanum sp.), and still shares many similarities with its wild relatives.
Tomatoes planted in shady spots or plants fertilised with too much nitrogen tend to produce more side shoots and less flowers. So, we recommend choosing a location with as much light as possible to promote fruit formation and reduce side shoots. You can avoid nitrogen excess by using a natural fertiliser with long-acting effect, like our Plantura Tomato Food. This releases nutrients evenly over an extended period of time which is gentle on the soil and prevents both deficiency and surplus of nutrients.
Advantages of pruning tomatoes
Removing leaves, shoots and suckers from tomato plants has several advantages. With beefsteak tomatoes, pruning prevents side shoots from developing heavy, large fruit that the plant cannot bear and would just break off. This usually improves the quality of fruit too, allowing the tomatoes to develop a stronger aroma as the plant has less fruit to supply. The plant will also concentrate more on fruit formation and straight stem growth. That way the plants grow taller but narrower, requiring less space. Another advantage is better air circulation as the plant will dry better after rain, which in turn decreases the risk of fungal diseases.
Tip: You can make tomato fertiliser from the sprouted side shoots. The method is the same as with nettle tea fertiliser soak the shoots in a ratio of 1 part shoots to 20 parts water. Apply this extract when watering to strengthen your tomato plant.
Recap – Advantages of pruning tomatoes:
- Prevention of thinner side shoots that break under the weight of heavy fruit
- Increased quality of fruit
- Stimulation of upright growth and production of fruit on other shoots
- Less space is taken by the tomato plants
- Better air circulation around the tomato plant
- Removed shoots can be fermented to produce plant-strengthening fertiliser
Disadvantages of trimming tomatoes
Of course, there are also arguments against pruning tomatoes, otherwise the topic would not be so controversial. Essentially, tomatoes should only be pruned when it makes sense – which is not always the case. Pruned plants tend to grow taller, which makes them less stable. A light gust of wind can knock them over or break them. So, pruned tomatoes always need to have some sort of support.
A major disadvantage of pruning tomato plants is that pruning causes open wounds on the plant, which are entry points for pathogens. This causes stress for the tomato plants, as they must close their wounds quickly and focus their energy on fighting pathogens. And not to mention the fact that regular pinching out or pruning is time-consuming and must be repeated every two weeks or so, depending on the vigour of the tomato variety. For beginner tomato growers, it can also be challenging to distinguish which shoots to remove. There is a risk of removing main fruit-bearing shoots, forcing the plant to switch to more unstable side shoots.
Recap – Disadvantages of tomato pruning:
- Not recommended for every tomato variety
- Some sort of support for the plants is absolutely necessary
- Pinching out causes wounds, making the plant susceptible to diseases
- Pruning is time-consuming and must be repeated regularly (every two to three weeks)
- For beginners it can be difficult to distinguish between main shoots and side shoots
How to trim tomato plants: tomato pruning guide
When to start pruning depends on the planting date. Ideally, start removing side shoots immediately after planting, so at the beginning of May in the greenhouse or from mid-May outdoors, and continue until autumn. It is best to pinch out your tomatoes in the morning, as the wounds dry quicker during the day. Wear gloves to avoid sticky green spots on your hands.
How to distinguish between suckers (side shoots) and main shoots? Tomato suckers always develop in the leaf axils (the point where the leaf meets the stem) of developed leaves. They grow at a 45-degree angle away from the main shoot. You will see that they are still thin and bendy. Check all the leaf axils of the tomato plant from top to bottom, so you do not miss any. Removing these side shoots is a process called pinching out. There are two ways to do this: you can either cut off the stem close to the main shoot using the fingernails of your thumb and index finger (this technique is called pinching out), or, better still, cut them off with a sharp knife or clean garden shears. Try to make a clean cut to prevent damaging the main shoot. You can also simply break off small shoots, as they come off easily.
Tip: When watering, make sure that the wounds do not get wet in the first few days after pruning or pinching out, to prevent increasing the risk of infection.
Summary of how to prune tomatoes:
- Pruning in the morning lets the wounds dry during the day
- Use gloves to avoid green stains on your hands
- Check all leaf axils of the shoots from top to bottom
- Break or snap off small side shoots with your fingers; cut off larger ones with a clean knife or gardening shears
- Keep the wounds dry when watering the plant
- Repeat roughly every two weeks, depending on growth
Pruning different tomato plant varieties
Pruning cocktail or cherry tomatoes
Cocktail tomatoes form small fruits and therefore only require limited pruning. This is because the side shoots usually form flowers and fruit quickly, plus the side shoots although thinner can support the weight of the fruits. However, to avoid a wild-growing plant with poor air circulation, it is worth removing a few shoots. If there is enough space, leave two or three lower side shoots next to the main shoot. The shoots will form flowers and fruits, and you can remove all side shoots higher up on the main shoot.
Pinching out bush tomatoes
Determinate bush tomatoes do not need any pruning or pinching out! These plants usually only grow to one meter tall. They have dense branching and bear fruit on the side shoots. If you pinch out the side shoots, you will just reduce the plant’s yield.
Indeterminate and beef tomatoes
Opinions vary on pruning medium-sized indeterminate tomatoes and beef tomatoes, which can weigh up to one kilogram or more. Usually, indeterminate tomatoes grow best with one or two low side shoots; so, remove all side shoots above this. The lower shoots help make the plant more stable and is where they bear fruit. With beef tomatoes, on the other hand, leave just one side shoot at most other than the main shoot and tie them both up. Alternatively, remove everything but the main shoot to grow directly upwards. Otherwise, the heavy fruits may cause side shoots to break off and lead to the plant bending.
For more helpful tips read our article on growing the perfect tomato.