Canadian lettuce grower slashes propagation time with LEDs

A year after converting the lettuce section of its 17 hectares of vegetable and flower greenhouses to all LED lighting, a British Columbia grower is reporting positive results. No real surprise there, but what stood out in the farm’s assessment was the impact that the lighting had on propagation — the early growth stage.

“One thing that we should mention is that we’ve gone to LED in our propagation whereas before we were propagating with HPS [ high-pressure sodium], and the difference in propagation has been day and night,” said Bill Brar, co-owner of Canadian Valley Veg Product at Canadian Valley Growers in Aldergrove, BC. “Crop time has been knocked down by almost 30%. And the product coming out of propagation (has) much, much more roots, and (is) a really nice stacked plant.”

Prior to the LED installation, Canadian Valley had considered combining LED and HPS lighting in both the propagation and finishing section of its lettuces, which occupy less than a hectare of the group’s total crop area. It decided on all LED, deploying about 1500 Philips GreenPower toplights from Signify in late 2019. Brar and his crew have focused on butter lettuces but have also used the lights for multi-leaf lettuce and are now beginning to use them for teen leaf lettuce as well.

The farm is using a higher intensity for propagation than for the final stage section, at 220 µmol/m²/s compared to 110.

“By going to a more intense LED in prop, what we’re seeing is a more even and consistent plant,” Brar said in a Signify video. That, in turn, helps to deliver a finished product in a more predictable timeline. Brar noted that not only are the lettuces growing faster and with more root mass, but they also have “a heavier leaf mass” and “better color.”

It is not unusual for growers to use LEDs both in the propagation and final stages, but it is notable that Brar singled out the improvement in the propagation stage.

The spectral content of the lights at Canadian Valley is preset at a static level. While Signify offers dynamic, changeable spectral control for lights in enclosed vertical farms that don’t rely much on natural light (or at all), its greenhouse lighting tends not to include changeable spectra.

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

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