Philips says LEDs make a rosier rose

A newly tuned light recipe has improved the quality among growers in Holland.

Shakespeare wrote that a rose by any other name would smell as sweet. But could a rose grown under an LED light smell sweeter? We're not sure, although we know this: LED lights can help produce roses with longer stems and bigger buds.

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That's according to Philips Lighting, which said that growers in Holland have reported improvements in size after trialing Philips LED toplights tuned to a new light recipe that maximizes rose quality. And in the rose business, size matters, as bigger buds and longer stems carry commercial value in the “cut rose” market.

The newly tuned lights are part of the Philips' GreenPower line of horticultural lighting. Philips said its previous LED rose recipe improved yields but did not enhance the size of the rose. After fiddling with frequencies, intensity, and duration, Philips and its partners claim to have now cracked that part of the quality equation as well.

"The rose branches under the new spectrum are longer, heavier, and have bigger buds," said Marc Koene, owner of Dutch grower SK Roses, one of about 30 entities including other producers, academia, and research institutes that have been working with Philips to advance the horticultural lighting technology.

"The feedback from this network helped us improve the quality and quantity of roses grown under LED lighting,” said Udo van Slooten, business leader horticulture at Philips Lighting.

SK, based in Den Hoorn, Holland, has been trialing the new lights in a small section of one of its greenhouses since January. Two other commercial grower have also sampled the new recipe, although Philips declined to reveal their names. Other partners include Dutch horticultural research institute Delphy and Holland's Wageningen University.

The name of the rose is “bigger” under Philips' specially tuned GreenPower toplights. (Photo credit: Philips Lighting.)

So what is the secret sauce that Philips and the 30 partners came up with? Philips is not saying. “The recipe is part of the knowledge that we have built over time, and cannot openly be shared,” a Philips spokesperson told LEDs Magazine.

The recipe appears to be in the 400–700-nm range of light (the PAR or photosynthetically active range, which more or less corresponds with visible light). Philips said the recipe is available with the newest generation of GreenPower LED toplighting, which it says delivers 500 or 600 micromoles per second (µmol/s) per light module. In horticultural lighting, micromoles represent the number of photons in the PAR range that hit a surface. Philips claimed the new toplights are very energy efficient, delivering 3 micromoles per joule (µmol/J). Philips guarantees the lights to last 35,000 hours.

Philips' rose recipe is yet another example of how the horticultural industry is using tunable LED lighting to optimize crops, including the use of the ultraviolet spectrum (not part of the PAR range) to enhance the appearance, potency, smell, and taste of plants, as LEDs has covered many times, including in its Horticultural Lighting Conference post-event report.

While Philips can now claim that its toplighting improves rose yields and size, it told LEDs that its research to date has not included rose fragrance. Whether a more aromatic rose is to be or not to be remains to be seen under the LED lights.

MARK HALPER is a contributing editor for LEDs Magazine, and an energy, technology, and business journalist ([email protected]).