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"The most interesting project in my career as a horticulture specialist'

Converting a cannabis greenhouse to a strawberry facility

As quick as cannabis was being catapulted in the last years ago, just as fast it got back to more normal growth in the horticulture world. Big cannabis players didn’t want to lose any time and invested millions of dollars in the older greenhouse to produce cannabis to be in production as fast as possible,  but after their dream disappeared, lots of these greenhouses came for sale again. They were converted back into fruit or veggie production greenhouses. This also happened in a project horticulture coach Bert van Geffen participated in. He calls it his most interesting project ever. 

As a horticulture coach, Bert helps growers to answer the daily questions they have with growing. He has built up over 45 years of experience growing different crops in different climates, all over the world. “This knowledge helps me to be of better service to my clients,” he says. “I have never encountered this kind of project in my life.”

The cannabis glasshouse structure that was being converted to strawberry production was already about 25 years old. “The size was standard, 4.5 meters high, and a bay width of 8 meters. It was set up with 10 plant gutters per 8 meters for cannabis. And we had 240 µmol led light standard RB spectrum nothing special so far. But because of the cannabis, it had a shading screen and a blackout screen and we have dehumidifiers to control the humidity," Bert shows.

"We all have to make sure we can make some money"
The most important questions for Bert were, how can you, if ever, grow strawberries in a greenhouse, like this?  “Also in the horticulture world, we all have to make sure we can make some money. Therefore we are always looking for less expensive ways to grow crops, with the highest production and quality. At the same time, we knew that we were not able to make the same investments as they do in the cannabis industry, because we wouldn’t be able to make money anymore.”

It was time to start thinking practically. “10 gutters per 8 meters are perfect, but they were all on the same level, and too low to grow strawberries. On top of that, the construction was not strong enough for hanging gutters. So as a first solution, we lifted all the gutters by 25 cm. And off we were," Bert explains.

Fire damage
A couple of months into this interesting project and also a couple of months before the facility was taken into use, there was a fire. This caused a lot of damage, the whole warehouse, irrigation-room, boiler-room, power supply, cold storage, and computer systems were gone. There was nothing left, except the greenhouse itself – even more challenges to deal with for the team!

"The first plants arrived in February this year, and we had to water the plants with a borrowed spray pump,” Bert recalls. “Meaning we had to drive the tank around with a bobcat to fill it at the main water supply from the city. Slowly on we managed to change one empty container to the irrigation room. We connected the city water to the existing main feed lines and added some dosatrons to feed the plants, the valve we had to open by hand." 

Also many of the windows needed to be fixed, as a lot of rack and pinions were gone. "From the start I was convinced this this was a huge challenge, but we managed to get it all done. In time, everything was changed over to strawberry production."

Hotter summers lead to winter production
Because the Canadian market likes to have a flat berry production, the team choose to only work with ever-bearer varieties and replant over the whole season. “This way we are in production 12 months a year, without high production peaks and low production periods. The challenge now will be the summer. Summers are getting warmer, and this makes growing strawberries more challenging. This summer the temperatures went over 40 degrees and for many weeks over 30 degrees, while the nights were warm as well."

For that reason, Bert expects that growing strawberries in winter will eventually become more profitable in winter than in summer. After all, during winter production, LEDs and blackout screens help keep the heat and CO2 inside the greenhouse. "Previously, I would never have thought of putting blackout screens and dehumidifiers in a strawberry greenhouse. Yet, as they were already present, we made the best use of them. This is a wonderful example of the out-of-the-box thinking that horticulture needs."

"The previous winter we did some testing under growing lights, just to see what can go wrong, and same as with other crops under the LED lights the conditions are much better to control than in the summer. We can't wait to see how this winter will go, in this 8 ha facility.  Summers are always challenging, either too hot, too wet, or too dark, you name it. Strawberries under growing lights are still in a learning phase, but I have no doubt that this will follow the veggies very fast," Bert concludes.

For more information:
Bert van Geffen


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