"We want to identify when you need far-red in particular and when you might still be able to decrease this"

Signify has provided Van Wordragen Flowers BV with a full LED installation, including a light spectrum with adjustable far-red. This makes the chrysanthemum grower the first in the Netherlands to use this technology from Signify. The system, which is set to be launched at the IPM, consists of the Philips GreenPower LED toplighting force with an energy-efficient spectrum of red, white, and blue light and, in addition, far-red LEDs which can be steered separately for better elongation. This LED toplighting force dynamic was installed at Van Wordragen in September 2022.

Grow lights with adjustable far-red LEDs
“Of course, the high energy prices were a significant reason for the switch to full LED,” explains owner Hein van Wordragen. “What made the difference, as far as I was concerned though, was the research by WUR into controlling elongation and response times with far-red light.” According to the results, chrysanthemum stem length can be properly regulated with full LED by providing subsequent end-of-day lighting with 30 minutes of 20 μmol/m²/s far-red light. This research puts an end to the fear amongst chrysanthemum growers that the use of full LED might result in too short flower stems in the winter. Another benefit of using far-red in this way is a potential reduction in the cultivation period by a few days and less shoot growth at the base of the plant.

“I had every confidence in the research carried out by WUR and eventually got in touch with Signify,” says Van Wordragen. “They then suggested the Philips GreenPower LED toplighting force dynamic with adjustable far-red light.” Leontiene van Genuchten, Plant Specialist at Signify, explains: “We have already previously trialed adjustable far-red, but at the time, it was mainly about the growth rate instead of elongation. This is also because there were still a lot of hybrid lighting systems at the time, where elongation was not an issue.

Further research
Meanwhile, further research by WUR has demonstrated that subsequent lighting with far-red also has positive effects on crop elongation when illuminated for shorter periods and using only 10 or even 5 μmol/m²/s far-red. Furthermore, the practical application at Van Wordragen next winter will yield a lot of new information and insights. “We are all going to learn a great deal,” says Van Wordragen. “The results are highly encouraging so far.” Signify has also been closely involved. Van Genuchten: “Every week, we harvest a small section to see how long the stems are. If you then compare this against the amount of far-red applied and the use of plant growth regulators, it is very enlightening. We want to identify when you need far-red in particular and when you might still be able to decrease this; if you use energy, it needs to serve a purpose after all.”

Pioneering role
“My old HPS lights were also from Philips, and for such an important step, I do prefer to choose trustworthy partners,” says Van Wordragen to explain his choice of Signify. “I am the first chrysanthemum grower in the Netherlands to operate with this Signify solution, but I didn’t want to feel like a guinea pig.” He does acknowledge his pioneering role in this, however: “In the chrysanthemum sector, we have a reasonably open relationship with one another and share relevant information in terms of cultivation. This is something we will also be doing here. It may not be the only solution for safeguarding the future of the Dutch horticulture sector in light of current developments, but it is undoubtedly a very large and significant first step!”