‘ReduSol forms the basis of hydrangea shading strategy’
Hydrangea cut flowers are very sensitive to irritants, in particular the white varieties. As a result, you always have to play it safe. Sijben Hydrangea uses the ReduSol coating as the basis of its shading strategy and uses the energy screen at times when too much light still enters the greenhouse.
Martijn Sijben has been growing hydrangea cut flowers since 2013. Initially the hydrangeas were grown in a rented greenhouse in Weert in the Netherlands. For the past two years the hydrangeas are being grown in his own 2.2-hectare greenhouse in Helenaveen. These are magnificent, beautiful, large flower blossoms coloured blue, pink and white. He sells them through the FloraHolland and Rijn Maas flower auctions. To gain wider recognition for his product, he has joined the Paletti Growers cooperative. This is a group of ornamental flower growers in the Province of Noord-Brabant, the Province of Limburg and the bordering German region, that aside from joint promotion, purchasing and transport also form a source of mutual inspiration. An enthusiastic group of ornamental flower growers.
Sensitive to irritants
Hydrangeas are known for their sensitivity to light. Ideally, the greenhouse should always be somewhat dim. ‘Hydrangeas are highly sensitive to irritants and quickly become imbalanced, which causes the flower petals to become burnt. This happens even faster in white varieties than other varieties. In fact, it is difficult to say whether this is due to too much light or too much heat, and it’s probably a combination of both,’ says Sijben.
For this reason he has been using the light and heat reflecting ReduSol coating since the start-up of his business. Agricultural contractors apply a layer to the greenhouse roof at the end of April or the beginning of May. ‘Young crops are given a thin layer at the beginning of April. A second layer is then applied on top of this at a later date. We apply a single layer for two-year old crops,’ he says.
‘This was not enough during last summer’s heat. We then had an extra layer of ReduSol applied towards the end of July.’
Use of a screen
In addition to the coating, it is also necessary to use the energy screen at extremely hot times in summer. ‘This often happens around noon. If we don’t do this, the flowers will start to show signs of wilting in the afternoon. Furthermore, we have to pay careful attention to ensure the flower petals do not become burnt when we slightly open the windows. The open windows still allow direct sunlight to enter the greenhouse which can cause burning. To prevent this, we adjust the window settings. For example, we may open one side and close the other side. We then combine this with the use of the energy screen.’
Sijben is also giving thought to other shading strategies to refine his system. ‘I would like to have more flexibility: more light on darker days and more shade on lighter days.’
His colleague hydrangea growers also use ReduSol. Everyone uses this coating as the basis of their system. In addition, the system can be fine-tuned in various ways, whereby a screen is an essential element. ‘Some colleagues also use two screens and a misting system. But this requires additional investment. With our system – ReduSol possibly combined with a new screen in due time – we are able to produce high-quality flowers.’
Anne Elings explains why crops grow better with more light
For a good part of the year, the level of natural light is below optimal for most crops. Any additional light that then enters the greenhouse contributes to improved production and quality, says Anne Elings, Plant Physiologist at Wageningen University & Research.
Lilies protected under ReduSol
Growing lilies without a shading agent is just about impossible. J&R Groenewegen of ’s Gravenzande, the Netherlands, have been using ReduSol for as long as it’s been on the market. “We are really pleased with it; we’ve not tried any other manner of shading since.”