There’s a lot of talk in horticultural lighting circles about controls that allow spectral shifting to suit different crops. Still, many lighting systems are hardwired for a specific cultivar. That’s certainly the case with a new Signify offering, aimed at strawberries in a couple of Belgian greenhouses.
Growers Fresa and Fragaria will soon deploy Signify’s FR_5 recipe in luminaires at new greenhouse space under construction in Beveren and Oostkamp, respectively.
The “FR” denotes the far-red portion of the light recipe emitted from a strawberry-specific version of Signify’s GreenPower TLC (toplighting compact) fixture, which is the smaller of Signify’s two horticultural toplighting LED luminaires, measuring 28.4×9.4×3.5 in. The mix also includes red, blue, and green.
Signify has honed the recipe not just for strawberries in general, but for only some varieties, which it declined to identify.
“Some varieties perform better without additional far-red light, others clearly benefit from it,” said Signify plant specialist Peer Hermans. “If the so-called ‘ideal light recipe’ for strawberries actually exists, it is yet to be discovered. The fact remains that this solution really works for several companies.”
Fresa and Fragaria believe the recipe will serve them well.
They will use the LED lights in a 2-hectare greenhouse that will join the 4-ha and 2.5-ha greenhouses already on the premises.
“We really wanted to grow and optimize our energy usage,” said Alain Lutz, who co-owns Fresa along with his wife Hilde van De Vijver. “In order to achieve this, we must be able to produce year-round, so we needed grow lights.” In a reference to the higher energy consumption of high-pressure sodium (HPS) light sources, he described HPS lamps as “far too expensive to use at the current prices,” and added that “full LED is the only option for us, but specifically with the addition of far-red light.”
Over at Fragaria, co-owners Kris Deguffroy and his son Cedric are providing a good reminder that far-red is not always the way to go for strawberries. Fragaria is adding a 5-ha greenhouse to go along with the 3.5-ha one it already operates.
While it will use Signify’s FR_5 on 2.5 ha — the area dedicated to winter growing — it will not use the far-red spectrum on the other 2.5 ha, dedicated to spring and autumn growing.
“Little daylight is available in winter, and the lighting installation provides a large part of the total light sum,” explained Signify’s Hermans. “When the grow light contains too little far-red light, some strawberry varieties can stay very compact. The leaves intercept less light and are quickly in each other’s way, at the expense of photosynthesis. Less stretching of the trusses also means that the fruits will not hang as low, making the harvest more difficult. Furthermore, a more open crop produces a more favorable microclimate.”
Fresa and Fragaria are both deploying Signify’s Philips GrowWise Control System but will use it to vary light intensity, not spectral makeup.
The FR_5 spectrum contains red, blue, green, and far-red light. The far-red light provides more opportunities for strawberry growers — among others — to set up an efficient, high-quality winter production, or to optimize their existing production. Varieties that stretch less easily in the depths of winter with full LED without far-red light often do better with this new spectrum.
MARK HALPER is a contributing editor for LEDs Magazine, and an energy, technology, and business journalist ([email protected]).
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