Should you prune cucumbers? Some people prune suckers off tomatoes and if it is a good idea for tomatoes, would it not also be a good idea for cucumbers?
If you decide to prune, which pruning method is best. Some prune out sucker, others remove lower leaves and still others even prune out excess fruit. Is pruning cucumbers a myth or not?
Do Cucumbers Have Suckers?
Cucumbers are vines just like tomatoes and they grow in a very similar fashion. Each node produces the main stem, a tendril used to wrap around things, a flower and a sucker. If this sucker is allowed to grow it produces a side branch which starts behaving just like the main stem. Before long you have two main stems both of which produce more nodes, more flowers and more main stems.
The arrow in the above picture points to a sucker.
Removing Suckers on Cucumbers
To remove a sucker, simply grab it and pinch it off, or cut it off, just like a tomato sucker.
Should You Remove Suckers on Cucumbers
There is lots of advice online and on YouTube that says you should sucker cucumbers. Such sites also make claims for higher yield and less disease, but never actually show any evidence to support these claims.
If you watch some of these videos you will notice that they are growing cucumbers in a greenhouse, or plastic shelter which has limited space to let the vine roam along the ground. To manage the vines they are grown vertically, usually one vine per vertical string. In such a situation, not pruning suckers would produce a big mess of interlaced vines. They have no choice but to prune suckers.
Traditionally, home gardeners planted cucumbers and just let them roam on the ground. Because space is not an issue, suckering is not required.
A third way to grow cucumbers is to grow them outside, but up a trellis. This is halfway between the two above techniques. It is vertical growing, but the vines are still allowed to form side branches and spread out.
Should you remove suckers on cucumbers? From a space perspective, it depends on your growing technique. In a greenhouse, plants are usually suckered to a single stem. In a field, pruning is not needed. Growing on a trellis can be done either way.
Do Suckers Drain Energy From the Main Plant?
One of the reasons given for pruning suckers goes something like; “When you cut off a sucker, the energy that was going into its growth is redirected to the main stem and fruit production.”
This sounds reasonable, but it’s not really correct.
When the sucker first starts to grow, it does use energy from the main plant. But in a few days time, that sucker makes its own leaf which starts working for the plant and produces its own sugars (energy). By the time this side branch makes flowers it has several leaves and can support itself – energy wise. Leaves are never a drain on the plant.
Suckers do not drain energy from the main plant.
Do Suckered Cucumbers Produce a Higher Yield?
Another claimed reason for suckering is increased yield. If you remove suckers, will you get more fruit?
Yield can be measured in two ways; yield per plant, and yield per growing area.
Some studies show no increase in yield per plant with suckering and others show that yield actually goes down on a per plant basis, which correlates well with suckering on tomatoes. If you remove side branches, you produce less flowers and therefore less fruit.
A study looking at field grown cucumbers found that unpruned plants produced a higher total number of fruits, length, diameter and weight of fruits, compared to single stem pruning.
However, when pruned to a single stem, plants can be grown closer together, and so the yield per growing area increases. Most greenhouses have limited space and need to produce high yields so they plant closer together and sucker.
Will Pruning Affect First Harvest?
Removing suckers reduces the plants ability to develop enough leaves to support female flowers. Consequently, flowering and first harvest is delayed. If you have a long growing season you might not worry about this, but in cooler climates we want an early crop because the season is so short.
Unpruned plants resulted in 1.7 times as many fruits as pruning the fruit on plants up to heights of 30 cm. This was in greenhouse culture and looked at yield in the first 10 days of harvest. It shows that pruning can significantly delay the first harvest.
The same study found that “Total yield of unpruned plants and plants pruned up to heights of 30 and 60 cm was 1.47, 1.22 and 1.16 kg/plant, respectively. ”
Pruning delayed harvest and resulted in smaller production.
Removing Leaves From Plants
Some people also suggest that you should remove leaves from plants. They claim that it makes it easier for pollinators to find the flowers and it increases airflow, reducing diseases.
“Cucumber yield is directly proportional to leaf area. So, removal of more than one leaf at a time is not recommended.”
I found no evidence that removing leaves increases pollination.
Will Suckering or Leaf-removal Reduce Disease?
This is a common suggestion for many plants. Thin them out so that there is more airflow, which in turn reduces fungal diseases.
Except in extreme cases it is unlikely to make much of a difference. If disease pressures are high, you can simply plant farther apart and skip the pruning step. Removing too many leaves weakens the plant and makes it more likely to get infected.
A common problem with cucumbers is powdery mildew. Many believe that wet and high humidity conditions increase the spread of this disease. Fungal spores can travel long distances and if they are around they will find you plants. The spores do need a wet condition for some 7 hours to germinate and infect the plant. High humidity favors spore formation while low humidity favors spore dispersal. Soooo … if you keep humidity high you will be creating more spores in the future, but if you keep the humidity low the spores that have already developed are more likely to be dispersed causing more infection. Seems like a no win situation – for you, not the fungus. I don’t think that you can control humidity enough to have much effect on powdery mildew in the garden.
Removing a few leaves, or suckers is not going to change humidity levels significantly.
Controlling Powdery Mildew
The best way to control powdery mildew on cucumbers is to spray the plants before they show any sign of the disease. Commercial fungicides work, or you can try the Cornell formula as described in this link.
Should You Prune Cucumbers?
If you are growing on the ground using a traditional method there is no advantage to pruning cucumbers. Let the plants do their thing. You will get a higher yield per plant and you will harvest earlier.
If you are growing up a trellis you can increase the yield by removing suckers, but only if you plant closer together. You will also delay your first harvest. Unless you really need a large yield, I don’t see much advantage to suckering in this case. I grow up a trellis and just let the plants grow as they want. Less work, earlier harvest, good yield. I also need less plants.
Greenhouse culture is a different situation and if yield is important to you, suckering can be a benefit.
Pruning suckers on cucumbers does NOT increase yield, unless you plant closer together. It does however delay the start of harvest.
Growing Cucumbers
What about melon and watermelon plants? Because one plant usually produces only 1 or 2 fruits unlike cucumber plant. Do pruning necessary for this plant?
I doubt pruning will increase the number of fruits.