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Cucumbers turn yellow and fall off: What are the possible causes and what can be done to save the vegetables?

Finally they are here in mid-June – early July: the first small cucumbers. It will still take some time until they ripen. But then the bitter disappointment: the cucumbers turn yellow and fall off. What could be the reason and how can you prevent it? We explain what you can do about it.

Why do the small cucumbers on the plant turn yellow?

Cucumbers fall off how to prevent harvest save

There are many possible reasons why cucumbers suddenly turn yellow and fall off. We list the most common ones and offer solutions. However, the causes are very diverse. It is often impossible to tell at first glance whether the plants lack nutrients, the location is too sunny or the roots are rotting. Therefore, proceed as follows:

  • First, check the plants for signs of disease or pest infestation.
  • Then consider whether there has been a change in the weather in recent days. Periods of heat and drought can also have a negative impact on yields as can rain and high humidity.
  • Have you perhaps changed anything? For example, transplanted the outdoor cucumbers into the greenhouse.
  • Did you see bees or other pollinating insects around the cucumber plants or not?
  • Have there been severe temperature fluctuations in the last two – three weeks?

The cucumbers are not pollinated

Cucumbers pollinate male and female flowers

Cucumbers form their fruits behind a flower. On each plant there are few male and many female flowers and only the female ones form ovaries. If these are not pollinated, then the unfertilized cucumbers fall off.

Outdoor cucumbers are usually pollinated without problems. However, if the cucumbers are grown in a greenhouse, it should be ventilated daily for extended periods of time so that pollinating insects have access to the plants. Another option would be to pollinate the flowers yourself. The best way is to rub two flowers together. Repeat this process daily.

The soil is too wet or too dry

Cucumbers wrong watering and care fall off

If the soil is too moist, then the cucumbers can rot quickly. To prevent this, you can work in sand or clay. Especially for potted plants, good drainage is an absolute must.

Another possibility is that the cucumbers are not watered regularly. Water the plants directly around the root area. Depending on the variety, you should do this between three and four times a week. Mulching with grass clippings can also significantly increase the soil’s ability to retain moisture.

In the greenhouse, you should still pay attention to the humidity. If this is above 60%, then you should ventilate the room regularly to avoid rotting.

Cucumbers turn yellow: lack of nutrients

Cucumbers turn yellow and fall off how still save


The cucumber plant needs a lot of nutrients to form the fruits. The strong grower feels best when the soil is airy and rich in humus. So it is worth loosening the soil before planting the cucumbers. Furthermore, you can provide the plants with slow-release fertilizer at the start of the gardening season. However, this is not enough and they would then have to fertilize the cucumbers additionally weekly in the summer.

The plant bears too much fruit

Everyone is happy about a rich harvest. However, if the cucumbers bear too many fruits, then this can have a negative effect on the quality and some fruits may turn yellow and fall off.

The cucumbers turn yellow and fall off: Diseases or pest infestation

Cucumbers turn yellow and fall off how to save

The cucumbers are very susceptible to fungal diseases, the most common of which is powdery mildew. The disease is transmitted from plant to plant and can significantly reduce yields. In the worst case, the plants die. To prevent this, you should place the specimens in the ground at a minimum distance of 60 cm from each other. In this way, you can prevent rapid spread. The next step is then to cut off the diseased parts of the plant and treat the affected plants with an approved fungicide that is not harmful to insects or, even better, with a suitable home remedy. Prevention of fungal disease is quite simple: avoid waterlogging, do not water the cucumbers from above, the leaves should remain dry.

Cucumber plants are also often attacked by pests such as aphids and spider mites. Certain home remedies are effective against aphids. You can also use beneficial insects in the fight against the pests.

Frost damage and sun burns

Cucumbers turn yellow what to do


In some cases, if the temperature differences during the day and night are too great, you should protect the plants from frost damage with fleece in the evening.

The wrong location can also cause the fruit to fall off as a result. If the plants are sunny, then the direct light can burn the leaves. This will affect the yield.