Pruning cucumbers: how & why?

If you stick to a few rules, pruning cucumbers is simple. It can also help prevent diseases and ensure a good harvest. Read to find out more!

Everyone knows that tomatoes (Solanum lycopersicum) must be pruned. But what about cucumbers (Cucumis sativus)? Do they also need pruning and if so, how do you go about it? Here, we show you when to harvest cucumbers, and how to do it properly. 

Should you prune cucumber plants?

Opinions differ on whether it is necessary to prune cucumber plants. There is no scientific evidence that pruning increases fruit yield. However, there are still several good reasons to do prune your plants:

• Growth control: In a greenhouse, where space is limited, pruning ensures your plants grow up and not out.
• Disease control: Removing the lower side shoots and thinning out the foliage improves aeration, so the plant will dry faster. This is important, because cucumber plants are susceptible to soil-borne diseases and mildew.
• Fruit control: By removing unwanted shoots you ensure that your plant puts energy towards fruit growth and not leaf growth.

Disadvantages of pruning

There are some disadvantages to pruning.

• You may end up removing fertile side shoots.
• Pruning creates an open wound, which weakens the plant and leaves it open to pathogens. 

Tip: Prune in the morning and in dry weather so that the wounds dry quickly. Without water, most pathogens cannot take hold.

Weigh the pros and cons to decide whether pruning your plants is best. The good news is that, unlike tomatoes, you need only prune your cucumber plants once, because no new shoots will develop on a cut leaf axil.

Instructions for trimming cucumbers

If you do decide to prune your cucumbers, all you need are your fingers, and possibly a sharp knife for any thick side shoots. Start pruning at the bottom of the plant.

Which shoots should be pruned?

1. The greater the distance between the soil and the first leaf, the more difficult it is for pathogens to penetrate the plant. With that in mind, for climbing varieties, it is best to remove all side shoots that are within 50cm of the ground.
2. Check your young plants regularly for “prickly” shoots and remove them where necessary. If your cucumber plant is thriving, remove the lower leaves to help it stay healthy.
3. For shoots 50cm above the ground, regularly check the leaf axils for side shoots. Cut them off after the first couple of fruit sets.
4. If your plant is becoming too large, cut off the top of the main shoot at the end of the season. Any fruits developing here will not ripen anyway, and the remaining fruit will continue to ripen as usual.

If your cucumber’s side shoots are still small and fresh, pinch them off with your fingernails. If they are longer than about 5cm, it is best to use a sharp knife. This is because the larger the wound, the more damage is done to the plant and the greater the entry point for pathogens. 

Tip: To prevent the transmission of diseases from one cucumber plant to another, disinfect your knife between plants.

Deciding which cucumbers to prune is less an issue of cucumber variety and more an issue of cultivation style. The general rule is, once a cucumber plant requires a climbing support, or where space is limited (in a greenhouse for example), prune your plant. 

However, hothouse cucumbers, which are climbers, benefit from a prune, while outdoor cucumbers generally do not. Because gherkins and pickling cucumbers grow on the ground and have more space outside, they are also less likely to need pruning. 

If you are growing mini and snack cucumbers, pruning will depend on cultivation style. If you are growing mini cucumbers in pots on the balcony, pruning is unnecessary. In a narrow greenhouse, however, it makes sense to prune the plants.

Cucumbers tend to grow from two shoots. If this is the case for your plant, select the lowest side shoot, and train it to be the main shoot. In this way, you can remove all other side shoots, and leave only the fruit set in the leaf axils of the main shoots.

Tip: Cucumbers are highly nutritious and need sufficient fertilisation to ensure a rich harvest. In addition to various household fertilisers, such as nettle slurry or coffee grounds, our Plantura Liquid Tomato Food is an excellent way to provide the cucumber plant with enough nutrients. In particular, the fertiliser has a high potassium content, which is ideal for cucumbers.

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While you do not necessarily need to prune cucumbers, the same cannot be said for most tomato varieties. If you want to achieve high tomato yields, pruning is the way to go. Why not read up on pruning tomatoes to get the most out of your plants.