Harsh Canadian winters no obstacle for local vegetable production

Phil Tiemstra: ‘Growing vegetables at -30°C works just fine with LED and AVS’

Gull Valley Greenhouses is a 4.5-acre (1.82 ha) family business in Alberta, Canada. They grow several types of vegetables which are primarily sold at farmers’ markets in the wider area. The modest size of the business didn’t stop founder Phil Tiemstra from kitting out a new greenhouse with AVS air handling units in 2016. A second one followed in 2020. “I noticed straight away that crop performances shot up,” the grower says. “The climate also feels a lot more pleasant for us.”

Quirky character

Phil Tiemstra and his wife Carolyn are assisted by their son Levi and his wife Carmen. Finding his father's chicken farm too little of a challenge, he switched to growing vegetables in the 1990s. The business reflects the self-conscious side of the Canadian’s character. The double layered polytunnels are equipped for modern substrate cultivation and feature energy screens, pipe heating, LED lighting and, of course, the highly efficient AVS ventilation system. Working organically as far as possible, they grow a wide range of crops and varieties, with at least 15 different types and varieties of tomatoes, as well as beans and various types of cabbages. Taste and quality are a top priority at Gull Valley.

Not a day of regret

“I bought my first LED system for growing tomatoes in 2015, but I didn't manage to create a good climate in that greenhouse,” the grower recalls. “We needed air handling to improve things, and I had heard that Van Dijk Heating supplied interesting and affordable systems. So I opted for AVS without heat recovery. And I haven't regretted my choice for a day.”

Yields up by at least 30%

AVS excels in efficient moisture control without excessive heat loss. This system allows moisture to be removed and dry air fed in without having to open the energy screen or the vents. “That makes a huge difference in terms of energy consumption, particularly when you think that outdoor temperatures can drop to as low as -30°C here in winter,” Tiemstra points out. “It also keeps the climate more homogeneous, so the plants grow better and more evenly. I noticed straight away that crop performance shot up. Disease pressure dropped and yields grew by at least 30% in the first year. Without having to expand the business!”

Golden combination

Last year, the family business replaced one greenhouse with a new one, also equipped with LED grow lights and an AVS air handling system with central heating blocks. A third of the nursery is now equipped with what is a “golden combination” for Canadian conditions. That’s it for now, although Phil doesn't rule out the possibility of his son Levi adding more later on. “We are happy with our current setup,” he explains. “Thanks to AVS, we are getting much more benefit from our lighting system, and we and the plants all feel more comfortable in the greenhouses.

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