On Tuesday 09 October, a group of around 20 growers attended a GrowSave event on Air Movement, hosted by W. D. Smith and Son near Battlesbridge, Essex. The day was split into two sessions:

• The morning focused on the theory and some of the science behind generating air movement in greenhouses.
• The afternoon consisted of practical demonstrations in the greenhouse.

The event was led by Peter van Weel, who spent his career as a researcher at Wageningen University and Research in the Netherlands. He has a wealth of experience in optimising airflow around greenhouses, helping to improve crop health and resilience, while also offering energy savings. His knowledge was invaluable in helping delegates understand the influence of the myriad of factors which can lead to temperature variations in and around the crop. But, more importantly, leaf/flower temperature can be very different from the ambient air temperature and this is where problems can arise. To help combat this, an effective air movement solution is required.

Many growers will be familiar with traditional horizontal fan setups, which help to move and mix the large volume of air within the structure. However, typically these fans are placed high up and may not have the desired effect at crop level. This was highlighted by the smoke tests, which helped those in attendance to visualise where the air actually ends up. This is not always where the theory would suggest, with external factors, such as wind direction affecting the internal atmosphere.

An alternative to horizontal fans is vertical fans, such as the Nivolator. A representative from Nivola demonstrated the unit, which pushes air downwards in a conical shape, thus ensuring penetration of the crop canopy. From the tests, this appeared to be a more effective solution for the pot plants in the greenhouse. Whether the benefit would be the same in a taller or leafier crop remains to be seen, although one can imagine that the effect would be much the same.

A full event write-up will be on the GrowSave website soon.