Which is best for cannabis – a Dutch or North American greenhouse?

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By Omar Sacirbey

High energy costs and declining cannabis prices have many cultivators thinking about moving their indoor grows into greenhouses.

But once that decision is made, those cultivators must determine whether to buy a North American-made greenhouse or import one from the Netherlands, which has dominated the industry since the 1800s.

Though many believe greenhouses can produce a high-quality cannabis crop, cultivators still must weigh abundant questions about which type is best.

Are you driven by design features? Or do you seek better materials? Is it software that makes a difference to you? Or does quality of construction move you?

Finding answers to such questions can help cultivators decide between greenhouses from the Netherlands and North America, both of which have proponents who make compelling and passionate cases.

Dutch engineering and materials

Why choose a Dutch greenhouse?

“Better engineering. Better materials. Better construction versus U.S. greenhouses,” said Jay Czarkowski, a founding partner of Canna Advisors in Boulder, Colorado.

Proponents of Dutch-manufactured greenhouses, commonly referred to as Venlo style, say they are better engineered because their glass exteriors let in the maximum amount of sunlight, they are airtight to reach maximum levels of CO2, and their shading screens don’t create unnecessary shadows that can reduce yield.

Venlo greenhouses tend to be taller and have multiple peaks through which a grower can selectively vent the greenhouse to cool it.

An advantage of a taller greenhouse is that it enables the heat to rise, a process that takes the heat away from the plant. The greater amount of air volume in the greenhouse also slows the changes that occur to the environment, so plants don’t have to react as quickly to those fluctuations and, thus, avoid greater stress.

North American greenhouses, on the other hand, “are pretty simple engineering,” said Matt Cohen, CEO of TriQ Systems, an Oregon-based greenhouse engineering firm. “They’re more concerned about snow loads and season reliability.”

Another important feature of cannabis greenhouses are light-deprivation shades, designed to simulate nighttime conditions for plants.

Cohen maintains that Dutch shades are better because they are built into the greenhouses and can be rolled out or retracted as needed. North American greenhouse blackout curtains are “really clunky,” Cohen said.

Cohen also prefers Dutch greenhouses, arguing they have better automation software that controls things such as shades, climate, humidity, venting and irrigation.

The Dutch “control the algorithms that have figured out how to have these greenhouses have the maximum light, maximum CO2, with precision around environmental controls … at the lowest energy-use costs,” Cohen said.

“It’s only in these high-tech Dutch systems that you’re going to get the quality, yield and the lowest operating cost.”

North American engineering and materials

Why choose a North American greenhouse?

Josh Conley, CEO of Next Gen Greenhouses in Southern California, disagrees that Venlo greenhouses are made of better materials and are more airtight. For example, he has facilities that use twin-wall acrylic material, which he said is considered by many to be the most high-tech and efficient exterior material available.

“All the materials that are available to the Dutch are available to the U.S. as well. They’re not hiding any secrets,” Conley said.

North American greenhouses have other advantages, said Leigh Coulter, president of GGS Structures, a greenhouse manufacturer in Ontario, Canada.

“If you are looking for a strong greenhouse that will protect your crop, go with a North American manufacturer who uses American steel,” said Coulter, who believes U.S.-manufactured steel “is the best in the world.”

Likewise, not everyone is convinced the software automation in Venlo greenhouses is superior to that in North American greenhouses.

“There is no secret algorithm. There is only, ‘What does that plant need and how do you provide an environmental system to supply those needs?'” said Tom Vezdos, vice president of commercial sales at Rough Brothers Inc., a canna-centric greenhouse maker in Cincinnati.

Climate changes one’s needs

Dutch greenhouses are designed with the environment of the Netherlands in mind, which means below sea level, cloudy and relatively little sunlight.

“In my opinion, Dutch greenhouses for summer climates are really not superior,” said Conley of Next Gen Greenhouses. “They typically want one method of doing things, but climate scenarios change and thus the structure should, too.”

For example, Dutch greenhouses tend to use small, and as few as possible, metal members and high-transmission glass. Such a setup probably wouldn’t work in Florida.

“When 130 (mph) winds come through, that greenhouse may not be standing at the end of the hurricane,” said Conley, noting that Florida also has plentiful sunshine. “That’s where a more robust structure may be more suitable … Something that is polycarbonate and that can withstand those forces would be a better choice for Florida.”

Coulter of GGS Structures believes North American manufacturers offer more options.

“The style of greenhouse, covering options, automation systems and even material-handling systems all differ depending on where the greenhouse is located and how the grower is growing,” she said. “North American greenhouse manufacturers tend to be better at adjusting their product offerings to provide the best crop environment for each customer.

“Conversely, the Dutch systems are more geared toward fitting the grower into their system. They tend to have fewer styles of greenhouses to choose from.”

Bottom line

Ultimately, Coulter said, growers should think less about which country their greenhouse will come from and more about the companies themselves.

“There are some very good greenhouse manufacturers in North America, and there are some bad ones,” he said. “Just as in the Netherlands, there are good and bad greenhouse structure companies.

“A grower who only looks at the address of his greenhouse supplier is in for trouble.”

Omar Sacirbey can be reached at omars@mjbizdaily.com