How are greenhouse plants pollinated

Pollinate tomatoes in the greenhouse: instructions | Tomato flowers


For tomatoes to bear fruit at all, they must first be pollinated. In the open air, the wind and insects pollinate, whereas in the greenhouse some support from the hobby gardener is required. There are various methods available for this, which we will introduce to you in this article.

Growing tomatoes in the greenhouse has a number of advantages, after all, the plants can grow and thrive in a protected environment. A greenhouse offers optimal protection from the weather and at the same time the possibility of creating the ideal climate for the tomato plants. All of these are essential factors for a high-yield harvest, but tomatoes only produce fruit when they are first pollinated. In the wild, this process is carried out by the wind, bees and bumblebees. In the greenhouse, however, these factors are partially eliminated, which is why the hobby gardener has to help with the fertilization of the tomatoes.

Optimal conditions

In addition to natural helpers, other factors must also be taken into account so that tomatoes can be fertilized at all. First of all, the pollen has to be released and germinable. For this, in turn, certain requirements must be met, because both the humidity and the temperature play an essential role. If the humidity in the greenhouse is too high, the pollen can clump and / or prevent it from being released at all. However, if the humidity is reduced to a minimum, this affects the germination capacity of the pollen. In the greenhouse, however, the optimal conditions can be created quickly and easily:

  • ideal relative humidity: 50-80%
  • too humid: 80-85%
  • too dry: 50-80%
  • ideal temperature: 18-25 degrees
  • too hot: 30 degrees
  • Time: after the flower has opened, for about 2 days
  • ideal time: 9-10 a.m.

Note: Pollen is usually still stuck together in the early morning hours, so that pollination has little chance of success. Likewise, the scar dries out more and more as the time progresses and thus prevents the pollen from sticking.

Pollination by bees and bumblebees

While natural helpers such as bees and bumblebees can easily get to the tomatoes outdoors, they must first be given access in the greenhouse. For this it is advisable to open windows and doors regularly and leave them open during the day if the weather is suitable. If the beneficial insects cannot find their way into the greenhouse by themselves, they can be attracted with the right plants. This works best with bee and bumblebee friendly plants, which create an optimal incentive for the natural helpers:

  • Bumblebees: Buddleia, poppies, clover, clematis
  • Bees: basil, lavender, bee herb

If the greenhouse offers enough space, a bumblebee box can also be set up and bumblebees can be settled with it. This has several advantages for the hobby gardener: On the one hand, the bumblebees are settled directly at the desired location and can therefore fertilize the tomatoes more easily. On the other hand, a nesting aid is made available to the valuable insects.

Dust by shaking

The simplest and at the same time simplest method is to shake the plants vigorously. This movement causes the pollen to fall out and can subsequently be pollinated. Shaking the plant once is not enough, however, because the process should be repeated several times to increase the chances of success. As a rule, it is sufficient to gently shake the plants on the flower clusters every one or two days.

Pollination with a fan

In the wild, among other things, the wind takes over the pollination of tomato plants. Anyone who cultivates tomatoes in a greenhouse should therefore always ventilate well. It is also best to leave the windows and doors open in the warm season. However, if there is no wind for a longer period of time, the wind can be simulated using a fan. The device is simply set up near the plants for this purpose, but should not blow directly onto the plants at full strength. If you want to use this method, you can choose between the following devices:

  • Floor fans
  • hanging fans
  • Pedestal fans with swivel joint
  • Circulating air fans
  • Small room fans

The air speed affects the climate in the greenhouse because it influences the evaporation and temperature in the room. The stronger the fan is set, the faster the air draws through the greenhouse. This in turn removes heat and moisture from the greenhouse more quickly.

Electric toothbrush for pollination

A greenhouse does not always offer enough space for any equipment, so that fertilization has to be helped in another way. One possibility is the so-called “trilling”, in which an electric toothbrush is used. With its vibration, this simulates the hum and flapping of bumblebees' wings, which triggers pollination. The pollen is released and then falls onto the stigma so that the tomatoes can pollinate themselves.

  • Place the toothbrush on the stem
  • just above the flower
  • switch on the electric toothbrush
  • stop briefly
  • Repeat daily until fruit is formed

Tip: There are now so-called “tomato trills” on the market, which replace the electric toothbrush.

Pollination with a brush

If you only cultivate individual tomato plants in the greenhouse, you can completely fertilize them. A brush is required for this method, although at best this is also made up of real hair. A red sable human hair brush is available in many shops and is also comparatively inexpensive. Instead of a soft brush, you can use a conventional cotton swab. Regardless of the aid, this variant is designed as follows:

  • First, gently stroke the brush over the pollen sacs
  • Pollen collects in the brush hair
  • then gently stroke the scars

Tip: The brush should always be dry and never wet! Otherwise the pollen will stick or be washed away during washing.