flowering cucumbers, but do not produce fruit
Cucumbers, from the gourd family, have been cultivated for more than 3000 years. Today they are among the most commonly grown vegetables. There are strains that are exclusively grown outdoors and those that are predominantly grown in a greenhouse. Botanically, cucumbers are berries. They are cultivated on climbing aids or lying on the ground. Occasionally it can happen that cucumber plants flower but do not produce fruit or shed them.
causes
water
Insufficient water supply as a cause
If cucumber plants flower but do not develop fruit, this can be due to strong fluctuations in soil moisture or an insufficient water supply. This is especially true if they suffer from drought stress during and just after flowering. Then it can happen that the plants shed most of the fruit buds, existing young cucumbers die or show deformations. This applies to outdoor cucumbers as well as greenhouse cucumbers.
- Proper watering is essential for optimal growth and fruit formation
- Cucumbers have a very high water requirement
- they don't like waterlogging
- a larger amount of water is needed every day
- Soil should always be evenly moist
- daily water requirement of a single plant is up to three liters
- the irrigation water must not be too cold
- lukewarm water temperature optimal
- preferably use rainwater or stagnant water
Tip: When watering, you should also make sure that you only pour on the ground and not over the leaves. Otherwise, the moisture on the leaves could encourage bacterial or fungal growth.
Leaf of a cucumber plant
temperature
Temperature fluctuations and lack of light
Other causes of missing fruit can be strong temperature fluctuations (heat or cold shock). In order to be able to bloom and later develop cucumbers, heat is essential. This starts with the sowing, for which a germination temperature of at least 20 degrees is required.
Glasshouse
In a heated Glasshouse young plants can be planted out as soon as the temperatures are around 15 or 16 degrees both during the day and at night. In unheated houses it is better to wait until after the ice saints. in the outdoor it should be noted that the soil is already warm enough at the time of planting. It should be at least 18 degrees and slightly cooler than the air temperature. For outdoor planting, it is best to choose a sunny location.
deficiency symptoms
If the fruit does not form despite flowering or if they are shed early, a lack of light or nutrients and/or too high a salt concentration, due to over-fertilization, be responsible for it. In such stressful situations, the plant tries to protect itself from overload. Healthy and well-developed plants often have a very high fruit set. Since a plant is not able to optimally supply too many cucumbers, it can happen that young fruit buds die off.
pollination
Absent or fruitless pollination
Tried and tested cucumber varieties are usually monoecious, i.e. both male and female flowers are on one plant. In the meantime, in addition to the mixed varieties, the trade also offers new breeds with predominantly female flowers. They are called parthenocarpic (virgin-fruited) varieties. These cucumbers don't develop seeds, and most importantly, they don't need any pollination at all. They are therefore perfect for a greenhouse culture. In some cases, such varieties are also offered for outdoor cultivation.
Flower on a cucumber plant
pollination
Unlike these modern cucumber varieties, non-parthenocarpic cucumbers are dependent on pollinators for fruiting. Insects take on this task outdoors, provided it is not too cool and too humid. Persistently cool and damp weather can sometimes lead to reduced fruit formation, even in outdoor cultivation, and consequently to crop losses.
pollination in the greenhouse
In the greenhouse, pollination is a little more problematic, especially for non-parthenocarpic plants. Here it is not enough to shake the plants more often. Leaving the greenhouse door open for a short time to allow insects to fly in to pollinate is usually not enough. Then pollination by hand can be advisable. In order for this form of pollination to be successful, it is first important to distinguish between male and female flowers. Only a simple stalk can be seen on the male flower, while a small cucumber base can always be seen on the female flower.
cucumbers in the greenhouse
Instructions for pollination:
- the first flowers are usually male
- later, when the plants are stronger, female ones also form
- on closer inspection, recognizable by their ovary
- now pollination can take place
- first cut off a male flower
- remove all petals from this flower
- only the stamp remains
- stroke the pistil over the stamens of the female flower
- this completes pollination
Since cucumber plants keep producing new flowers over the course of their cultivation, this process has to be repeated at regular intervals.