“We have to deal very cold winters and very hot summers,” says greenhouse director, Howard Huy. “The radiation in summer is very high reaching 1150 Watt/m2. In addition, the weather is very changeable. On a clear day, it can be 35o C, but it can just as easily be 18o C with the same high radiation. If you don’t do anything the result is the same: the plants call it quits.”
Huy has 9 ha of greenhouses, both plastic, and glass. He grows tomatoes, cucumbers, peppers, and aubergines in many different varieties to spread the risk. The products are sold via traders in Canada and the USA – the greenhouses are just 50 kilometers from the American border, close to Lake Erie.
In the past, he used ‘normal’ chalk and later a diffuse coating. “We decided to try Transpar just to see if it worked. We started with it last year and it worked so well we will definitely use it again. Our search for a good coating has come to an end,” he says.
Without any protection from the sun, the crops receive a shock in the summer heat: They wilt, become sunburnt and suffer quality problems such as blossom end rot. “The climate is much more uniform under Transpar. The temperature is often 3 to 5 degrees lower. We see better production and higher quality as well as better fruit size,” says Huy.
Transpar lets through the light that is essential for photosynthesis (PAR light), but blocks out the heat radiation (NIR, near infra-red) so the greenhouse and plants remain cooler. In addition, this coating makes the light diffuse so that the light penetrates deeper into the crop. “I find it difficult to judge if the latter is an advantage in our case,” he says. “But at least we can close the screen later. Therefore, we get more light in the greenhouse while the plants are able to use it. They stay active for longer. You also notice that the humidity stays much better at the right level.”
The company hires a specialized contractor who uses a helicopter to apply the coating; it is removed again in September. “It’s always a bit of a gamble as to when to apply it. This year it was cold and cloudy, so we could wait. But the end of April is always a safe time,” he says.
He hasn’t yet seen any disadvantages by using the coating. “On an overcast day you’d prefer to be able to remove it, but of course that’s not possible. But in general, we are very satisfied with Transpar. It does what it should. Therefore, we’ll be using this coating again next year. We are very pleased with it.”