Pruning Cucumbers: Removing the Lowest Side Shoots and Topping the Vine

Why you strip the lowest five or six joints

A cucumber starts producing female flowers almost as soon as it is planted. At that point the plant has barely any root system, and if it is made to swell fruit the vine stops extending and the roots stop spreading. Removing the flowers and side shoots at the lowest joints is not throwing away a harvest, it is buying the second half of the season.

The other reason is airflow. Leaves and fruit packed against the ground catch soil splashed up by rain, and that is where downy mildew starts. Keeping the bottom of the plant open also keeps the soil around the stem cooler in midsummer.

1. What a fruit costs the plant A cucumber goes from flower to seven ounces (200 g) in seven to ten days. Carrying several of those on a shallow root system stops the vine dead.
2. Give it three weeks to root The first three weeks after planting are when the roots spread. A plant that builds its body in that window is a different animal when drought and disease arrive.
3. When in doubt, remove it At the lowest joints you will almost never regret taking something off. Err towards removal and the second half of the season is much steadier.

The urge to pick that first cucumber is strong, but a plant you hold back now keeps producing well into late summer. The difference is obvious.

Decide what happens at each joint

Count joints from the base, at each true leaf. Pinch shoots out with your fingers while they are no bigger than a fingertip: the wound is tiny and nothing gets in. Let them grow and cut them with pruners and you leave a wide cut, which is how gummy stem blight gets a foothold.

Top the main vine at the top of the net

When the main vine reaches the top of the netting, at around the twentieth to twenty-fifth joint, pinch out the tip. Let it keep running and everything goes to the tip while the fruit lower down stays thin. Topping pushes the side shoots into growth, and the center of production moves up the plant.

Top it too high and you cannot reach to pick or to train, and you end up with an impenetrable tangle above head height. Decide your upper limit by what you can comfortably reach on tiptoe and stop there.

1. Choose where to stop The top of the net, around the twentieth to twenty-fifth joint. In a vigorous year the plant gets there quickly, so let your own reach decide rather than the joint count.
2. How to do it Pinch out the growing point just above a leaf joint, with fingers or clean pruners, on a dry morning so the wound seals quickly.
3. What happens next Within a week the upper side shoots start moving. Keep two or three of them and the center of picking shifts upwards, which is what keeps you harvesting into late summer.

Stopping side shoots and sub-shoots

Side shoots are where the second half of the crop comes from, so they need managing rather than removing. The rule is simple: let each one carry its fruit, then stop it so the leaves it keeps are the ones feeding that fruit.

1. Stop side shoots two leaves past the fruit Once a side shoot has set fruit at its first or second joint, count two leaves beyond and pinch out the tip. Those leaves feed that fruit where it is.
2. Stop sub-shoots at one leaf Stopping a side shoot brings out sub-shoots. Rub them off at the base where things are crowded, or if there is space to fill, stop them at one leaf.
3. Judge by space, not by counting Rather than counting joints, ask whether there is room for another leaf to open there. A shoot pushed into an already shaded space will not fill its fruit.

How much lower leaf to strip

Once picking starts, work up the plant removing leaves below the fruit you have taken. Aim to keep 15 to 20 healthy leaves on the main stem at all times. Strip too hard and the plant loses the capacity to fill fruit, so take no more than two or three leaves per plant at a time.

Yellowing leaves and any showing the white patches of powdery mildew come off without hesitation, and they leave the plot. Dropped in the path they simply carry on shedding spores.

1. Two or three leaves at a time Take a few every three to five days as you pick. Doing it gradually is quicker overall than a single hard strip.
2. Keep 15 to 20 leaves Maintain 15 to 20 healthy leaves above the fruit you are picking. If counting is a nuisance, aim for dappled light reaching the ground.
3. Take the leaves away Leaves left in the path keep releasing spores. Bag them and take them off the plot, or dry them somewhere well away from the bed.

Strip lower leaves on a dry morning. Wounds that have the day to dry are much less likely to let disease in.

What happens if you stop training

Leave a cucumber untrained and within a fortnight the leaves overlap and you can no longer see the fruit inside. Fruit you cannot see is fruit you pick late, and an oversized cucumber monopolises the plant's resources until the female flowers above it stop setting. Abandoning training is, in effect, ending the harvest.

To rescue a plant that has already closed up, do not cut it back all at once. Take a few old leaves every three days to let light in. Strip it bare in one go and the newly exposed fruit and stems scorch and turn black.