Improving pollination in the greenhouse

Pollination decides fruit set, fruit size and shape. In a greenhouse or tunnel it depends almost entirely on the colonies you bring in and the conditions you give them. Improving pollination therefore comes down to a handful of levers. Below is each one in short, with a link to the article that goes into detail.

1. Keep colonies strong, and replace them at the right time

A colony grows, peaks and declines. Replacing too late costs flower visits; replacing too early costs money. Watch traffic at the entrance and flower visits rather than only the calendar. Read: is my bumblebee hive still active?

2. Use the right number of hives, in the right places

Too few hives leave parts of the greenhouse without visits; too many can damage flowers. Spread hives evenly, keep them out of the sun and away from heating pipes, and give them a clear flight path. Read: how many bumblebee hives per hectare, and where to place them

3. Choose the right pollinator for the crop

Tomatoes need buzz pollination by bumblebees; other crops can use honeybees or a mix. Read: honeybees or bumblebees in the greenhouse? and bees for pollination

4. Manage heat and humidity

Above roughly 30 °C bumblebees fly less and pollen quality drops; very humid or very dry air also reduces pollination. Read: heat and humidity: when pollination stops

5. Mind light, UV and the lighting schedule

Bees orient by ultraviolet light. Glass, films, screens and LED spectra all change what they see, and winter brings short days. Read: pollination under LED lighting and pollination in winter

6. Plan crop protection around your colonies

Check side effects, spray when bees are not flying, and close or move hives in time. Read: crop protection and bee or bumblebee colonies

7. Protect colonies against hornets and wasps

Hornet pressure makes colonies stop foraging. Read: Asian hornets and wasps at bee or bumblebee colonies

8. Check the result, per crop

In tomatoes, bite marks show whether flowers were visited; in strawberries and soft fruit, fruit shape tells the story. Read: how to check tomato pollination, strawberry pollination and blueberry and raspberry pollination

Measure to improve

Every lever above is easier to use when you can see what happens. Manual checks are a snapshot from days ago. HiveWatcher measures flight activity at every hive and flower visits in the crop, next to climate and light, per greenhouse and per section. You see which colony is fading, which section falls behind and what a change in climate or lighting does, while there is still time to act. See also pollination monitoring vs manual counting.