Pruning & pinching out tomato plants
The pinching out of tomato shoots is a controversial topic among gardeners. We reveal when it makes sense to prune tomatoes and how to prune a tomato plant properly.
Rarely does a topic divide tomato lovers as much as the removing of tomato side shoots. Some argue for consistent tomato pruning, always and with every plant, 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 explain how and why you should cut back tomatoes and give step by step instructions for trimming tomato plants.
Is pruning tomatoes necessary?
So, should tomato plants be pruned? In short, whether or not you have to cut tomatoes depends on the variety, the location and the available space, where the plant grows. We therefore show you in detail which tomato plants should be pinched out and why.
Do all tomatoes have to be pinched out?
The simple answer is no. For all large-fruited tomato varieties such as ox-heart and beef tomatoes, the side shoots should be removed. Even with the medium-sized stake tomatoes, you should only leave a maximum of two to three shoots, including the main shoot.
Which tomatoes should not be cut?
Low and small growing bush tomatoes and wild tomatoes should not be pruned at all. They bear flowers on all side shoots and thus bear fruit again. The yield is highest without trimming. With the small-fruited cocktail and cherry tomatoes, it depends on if you would like to use the plant to their full capacity: you can either let the tomato plant grow fully or let it grow with only several shoots.
How many side shoots should be left on the tomato plant?
Wild tomatoes from South America grow naturally from all leaf axils, because they lie on the ground and form a multi-branched shrub over time. The domesticated tomato (Solanum lycopersicum) has been selected from the ranks of these diverse wild tomatoes (Solanum sp.), but still bears strong similarities to its wild relatives. In addition, tomatoes planted in excessively dark corners or are fertilised too much with nitrogen tend to produce more side shoots and less flowers. The planting location should therefore be as full of light as possible in order to get more fruit instead of side shoots. Excessive nitrogen application can be prevented with well balanced, mainly organic fertilisers with long-term effects.
Advantages of pruning tomatoes
Removing leaves and shoots from tomato plants has a number of advantages. First of all, with beefsteak tomatoes, you prevent side shoots from developing heavy, large fruit that they cannot bear at all, which can result in breakage. The quality of the fruit is then usually better, and it tastes more aromatic, as the plant has less fruit to supply. In addition, the plant is encouraged to concentrate more on fruit formation and stem growth straight upwards. This means that the plants grow longer but remain narrow and require less space. Another advantage is the enhanced air circulation. This means that the plant will dry better after rain, which in turn decreases the risk of fungal diseases.
Tip: You can make a strengthening tomato manure from the sprouted side shoots, with which the plants are then watered. As with nettle liquid manure, use a ratio of 1:20.
All advantages of pruning tomatoes at a glance:
- Prevention of breakage of the thinner side shoots that are unable to support 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
- Tomato plants become better aerated
- Broken shoots can be fermented to produce plant-strengthening tomato manure
Disadvantages of trimming tomatoes
Of course, there are not only advantages, but also a few disadvantages to pruning tomatoes, otherwise the topic would not be so controversial. First of all, it is not always sensible nor practical to pinch out or prune tomatoes. Pruned plants have a tendency to grow longer and taller, which decreases their stability. A light gust of wind can knock them over or break them. Therefore, cut back tomatoes must always be well grown with some sort of support.
A major disadvantage of pruning tomato plants is that pruning causes open wounds on the plant, which are an entry way for various pathogens. This causes stress for the tomato plants, as they have to close their wounds quickly and focus their energy on fighting pathogens. Regular pinching out or pruning is also time-consuming and must be repeated every two weeks, depending on the vigour of the tomato variety. For beginners among tomato growers, it can be challenging to distinguish between shoot tips and side shoots. There is a risk that the fruit-bearing tip will be removed, and the plant will have to switch to the more unstable side shoots.
The disadvantages of tomato pruning at a glance:
- Not recommended for every tomato variety
- Using some sort of growth support or tying the plants is absolutely necessary
- Pinching out leaves wounds and facilitates the penetration of pathogens
- 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: instructions
The best time to start pruning depends on the planting date. Ideally, you should start removing unnecessary shoots immediately after planting, i.e. at the beginning of May in the greenhouse or in mid-May in the field, and finish in autumn. It is best to cut back your tomatoes in the morning, as the wounds dry quickly during the day. Wear gloves, as tomato shoots leave sticky green spots on your hands.
How do you distinguish between suckers (i.e. side shoots) and main shoots? Tomato suckers always develop in the leaf axils of already large leaves. They grow at a 45-degree angle away from the main shoot and are still thin and elastic. If you check all the leaf axils of the tomato plant from top to bottom, you won’t miss a single one. These side shoots can be removed in a process called tomato suckering. There are two ways to do this: you can either cut off the stem closely to the branch with your fingernails by using 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. Be careful and try to make a smooth cut and to avoid damaging the main shoot. Small shoots can also be removed, as they can still easily come loose from the leaf axils in which they are placed.
Tip: When watering, make sure that the wounds do not get wet in the first few days after pruning or pinching out, otherwise the risk of infection increases.
Summary of how to prune tomatoes:
- Pruning in the morning lets the wounds dry well during the day
- Use gloves to avoid green stains on your hands
- Check all axils of branches from top to bottom
- Break or snap off small side shoots with your fingers, cut off larger with a clean knife or gardening shears
- Keep the wounds dry when watering the plant
- Repeat about every two weeks, depending on growth
Pruning tomato plants: differences between varieties
Pruning cocktail tomatoes
Cocktail tomatoes form small fruits and therefore only need to be pruned to a limited extent. This is because the side shoots usually form flowers and fruit quickly, which can also be carried well by the thinner side shoots. However, in order not to get a wild-growing and poorly aerated plant, it is worth removing a few shoots. If there is enough space, leave two or three lower side shoots next to the main shoot. This means that the tomato is multi-stemmed. These shoots form flowers and fruits, and all higher stinging shoots along the main shoot are removed.
Pinching out bush tomatoes
Bush tomatoes should not be pruned or pinched out at all! The bush tomatoes usually only reach a maximum height of one meter. They branch strongly and bear fruit on the side shoots. If you clip out the side shoots, you will take out most of the fruit that this plant would have borne.
Stake and beef tomatoes
There are very different opinions on the pruning of medium-sized stick tomatoes and beef tomatoes, which can weigh up to one kilogram or more. Stake tomatoes can usually be grown with one or two deep lying side shoots without any problems; all side shoots above this should be consistently removed. The lower shoots give the plant stability and that is where they bear fruit. With beef tomatoes, on the other hand, one side shoot at most should be left next to the main shoot and both should be tied up well. Alternatively, all sucker shoots can be consistently removed and only the main shoot can be allowed to grow upwards. Otherwise, the heavy fruits overstrain many thin side shoots and cause the plant to bend.
You can learn about tomato varieties in this article. If you are unsure what kind of plants to grow alongside tomatoes, this article on companion planting tomatoes will help you. Lastly, all tips on watering and mulching tomatoes are summarised here.