Greenhouse Purple Lights

Q: At night when I drive along the QEW,  there is a greenhouse in Grimsby on the service road near Bartlett Road. They recently expanded it and now part lights up purple, there is a blue section and a yellow section. I am curious as to what the different-coloured lights do for the plants in the greenhouse.

A: The distinct purple glow emanating from Freeman Herbs certified organic facility off the QEW can’t be missed. Its new dynamic LED lighting is giving the greenhouse of herbs a nightclub vibe for drivers passing by in Grimsby.
The technology is actually targeting the plants with the spectrums of light they require to grow while saving the company energy.

“We’re doing this because it’s sustainable and environmentally friendly,” said Marco De Leonardis, manager of research and development at Beamsville’s Freeman Herbs. “We decided we’d spend more by trying to have a better impact on the environment.”

De Leonardis explained greenhouses that use bright yellow or white bulbs tend to be wasting a lot of energy because the plants use very little of the green and yellow spectrums of light in photosynthesis. He said plants mainly use red and blue spectrums, so that’s what the company is using with its new LEDs. Different colour spectrums have different effects on growing plants. De Leonardis said blue keeps the plant more compact, with shorter internodes, larger leaves and thicker stems. There are more cells which mean stronger flavour in herbs. Red promotes elongation. Cells are bigger, the plants will grow taller with longer internodes and will grow faster.

The purple glow seen at the Grimsby greenhouse is the combination of red and blue light. De Leonardis said greenhouses that have LED lights tend to have static lights with a fixed amount of blue or red. For instance, a greenhouse growing tomatoes may use 30 per cent blue and 70 per cent red light. He said Freeman Herbs is one of the most advanced greenhouses in Canada because it uses dynamic LED lights. They allow De Leonardis to change the ratio of colours to whatever he thinks would help the plants from anywhere wirelessly. It’s expensive technology — the LED lights are four times more expensive than traditional High Pressure Sodium bulbs — but he said the company will save in electricity costs.

“Because we’re 100 per cent organic, the ecological impact is very important too,” De Leonardis said. “If we use twice the amount of electricity for the same amount of light that the plants use, it’s not really sustainable. It’s the case of the principle of being organic.”

The dynamic LED lighting was introduced when the greenhouse added an extension a year ago that included diffused glass. Changing the ratios of colour means some days the greenhouse will look a brighter purple because of more red and other days it will look darker purple with more blue. De Leonardis said it will be very difficult for the average person driving by to notice the difference.

There were two weeks when he ran 100 per cent blue on a particular plant so drivers would have seen both purple and blue. The yellow lights that can be seen on one end of the greenhouse are in the old section. They are still the old less efficient HPS lights but are staying for now because they have more than 10 years of life left in them.

De Leonardis said the new LED lights are already showing positive effects.
“We’re seeing a big difference in the dark months now,” he said. “The plants are greener, they are fuller. Normally because of lack of light, they are weaker and slender. With the lights we can control that.”