Harf decided to combine HPS lighting with Philips LED toplighting and a double line of Philips LED interlighting between the rows. To provide as much light as possible, the LEDs are on for 18.5 hours a day and the HPS lights are on 17.5 hours a day, to gradually heat-up and cool-down the crop.
Harf’s previous HPS interlighting set-up generated quite a lot of heat in the middle of the crop. This was a major issue, especially in the warmer months of the year, because he had to vent a lot of air and he lost a lot of CO₂. With the new LED interlighting and toplighting solution, Harf can still apply additional lighting in the warmer seasons. That’s important, because cucumbers require as much light as possible.
Harf says, “The plants tell you what they need. You can see whether they have gotten enough light or not. You see it very quickly so you can adjust your light and temperature accordingly.”