What is the effect of LED light on plant growth? And how can you best integrate LEDs into your climate control system, among other things? These are the kinds of questions Jan Voogt regularly hears as a teacher in courses on Het Nieuwe Telen (The New Way of Growing).

Ever since the introduction of LED lighting, it has been observed that plants react differently to sunlight than they do to the usual Son-T lamps, writes Jan in a contribution on Greenhouse as an Energy Source.

He concludes that LED light is very efficient when it comes to PAR light, but that it distorts the natural plant balance in terms of energy, water, assimilation, and nutrient uptake at the same time.

"To get those balances back in order, additional measures have to be taken. In growing cells and multilayer cultivation (vertical farming), for example, there is usually intensive air circulation to achieve an even distribution of temperature and moisture, both horizontally and vertically. This also significantly increases evaporation and thus nutrient uptake."

How to do this in normal greenhouses is not yet entirely clear, Jan indicates. "A degree higher than normal, or an (extra) growth tube at the head of the crop or near the flower buds? Perhaps a different composition of the nutrient solution, or more (vertical) air movement? Or is hybrid lighting not so bad after all? Screens against radiation to prevent the crop from cooling down are very obvious in any case.

"One thing is clear: to make large-scale use of LED a real success, we will have to take more account of the natural needs and characteristics of plants, and not just focus on the technology," says Jan.