Light Dep

Industry pros share tips, tricks and equipment that growers need to reap numerous annual harvests, produce top-notch cannabis and enjoy their biggest profits yet

Photo by Stephen Conley.

*This story originally ran in the Summer 2016 issue of SunGrower & Greenhouse.

As the cannabis industry continues to shed its illicit status, many small-scale operations have attempted to ramp up production by using the same unscientific methods and equipment that have been employed since the days of the black market.

This may work for boutique growers, but many industry experts agree this is largely unsustainable. With greenhouse production being one of the fastest-growing sectors in the industry, experts say serious growers need to consider light deprivation to meet market demand.

“Light dep is the future of cannabis,” says Jonathan Valdman, president of Forever Flowering Greenhouses. “It’s where so much of the industry is going right now.”

Growers who want to be industry leaders need to employ light deprivation correctly, right from the start. Here’s a look at how growers can ensure long-term success using light deprivation.


Many industry experts believe light-deprivation greenhouses are the future of cannabis production,
due to their ability to control both the environment and the photoperiod in an energy-efficient manner.

Pros and Cons

For most operations, the perks of utilizing light deprivation far outweigh potential negatives.

Using light dep techniques gives growers the ability to produce consistent, high-quality crops even in inclement weather, and anywhere from one to four additional harvests per year. Because growers can better plan their production cycles, they can demand a higher price point by beating their competitors to market.

So why isn’t everyone doing it? There are a couple of caveats, the first of which is price. Installing effective light deprivation equipment isn’t cheap.

“Automation is the best way to do light deprivation, but the downside is capital investment,” says Matthew Cohen, CEO of TriQ Systems. “As the market evolves, people can get by with manual systems, but any company that’s going to be successful long-term needs automation.”

There are cost-effective ways to get around investing in a fully-automated shading system, but choosing a low-tech alternative can create additional problems. For example, the labor costs associated with maintaining the proper 12-hours-on, 12-hours-off schedule can be time-intensive. There’s also a higher potential for human error with low-tech systems.

Industry experts emphasize that growers need to have a set plan before diving headfirst into the complex world of light deprivation. It’s not uncommon for growers to find themselves trapped in construction hell because they didn’t design their facility for light dep at the start.

“There have been a lot of mistakes made,” says Howard Hughes, of Horticulture Services. “A lot of greenhouses were cold frames and not necessarily built for these (blackout) systems. Many times the structure isn’t strong enough for the retrofitting. Light dep gets very expensive unless growers plan for it in the beginning.”

Outdoor farmers, such as the team at Natural Mystic Farms, often use panda plastic” and hoop houses to produce two harvests per season.


Selecting the Shades

Growers have options when it comes to selecting the shade fabrics. Mauricio Manotas, president of textiles company Svensson, breaks the decision-making process into three fundamental points: energy concerns, greenhouse equipment and humidity control.

Growers that are interested in energy savings should choose a shiny surface like aluminum over a less-expensive white surface. For growers planning to use a lot of supplemental light, a white finish will optimize and even out the light inside the structure. To address concerns about humidity, Manotas says growers need to choose breathable fabrics or materials that will prevent water droplets from forming, as this invites crop-killing diseases like botrytis into the greenhouse.

Growers can also select a fire-rated product in case the worst happens. From there, the installation, seals for fabric gaps and specific screens depend on where the operation is located and how the greenhouse is set up.

While each operation is different, many growers tend to prefer triple-layered blackout screens.

“I’m not sure if it’s a long-term trend, but it comes from the fact that they used to grow indoors,” Manotas says. “Two layers of blackout screen will do it. Three is overkill, but it’s peace of mind.”

Some of the reason growers balk at the idea of having fewer screens is that they can still see in a greenhouse with blackout shades extended. The perception is that having any visible light — as opposed to a pitch-black warehouse — is going to cause undesirable characteristics. That’s not necessarily the case.

“The eye sees more light than a plant sees,” Valdman says. “At zero lumens of light, we can still see. Growers don’t need 100% darkness for light dep, and we’ve found that minor pinholes that create starlight in the tarps aren’t an issue.”

Automated greenhouses use the same concept on a more permanent scale.

While some growers remain adamant about total blackout, this is another piece of conventional cannabis-growing wisdom that’s being challenged as the industry evolves.

Manotas expects growers to seek out whatever growing methods and equipment result in the biggest profit margins. Following the path of non-cannabis horticulture, that means greenhouses.

“Growers can control different zones and sections of the structure — one zone for flowering, another for harvesting, etc. — using less energy,” he explains. “We feel things are going this way when the market balances out.

“Right now, the demand is way higher than the supply, but eventually, growers will get real prices for their crops and have to improve their efficiency.”

Selecting the right blackout system and curtains are crucial for a successful light dep greenhouse.


Equipment Guide

The planning and research involved in creating a viable five-year plan can be overwhelming. That’s why equipment manufacturers recommend growers seek the advice of trustworthy companies and experts.

“It’s important to work with a company that knows that they’re doing and knows that product really well,” says Jon Kozlowski, cannabis greenhouse specialist at Growers Supply. Speaking to manufacturers who take the time to understand a grower’s budget, setup and unique needs can be a life-saver, especially when the structure needs to comply with specific building codes and requirements.

“This is regularly overlooked by growers, many of whom are surprised by expensive road blocks,” Kozlowski says. “No growing situation is the same. We’ve completed projects that have had some pretty specific requirements and requests.”

After growers take all the various factors into consideration, they’re ready to select from a number of options, ranging from do-it-yourself setups to advanced automated systems.

Even with automated systems, however, a grower’s success is dependent on having a system that is properly designed and installed. It must fit the structure’s shape without bunching or casting shadows.


High-Tech Light Dep

Overwhelmingly, equipment manufacturers agree the biggest trend in light deprivation is greenhouse automation.

“Growers are moving outside the warehouse mentality,” Valdman says. “A greenhouse allows them to lower the cost of production and the cost to the environment, which is a great way to add value to the product. I like to see cannabis producers becoming responsible growers.”

“We’re seeing more and more growers turn to the combination of greenhouses and light deprivation systems,” Kozlowski adds. This gives growers the control of an indoor facility, while providing sun-grown energy efficiency.

“Growers that use these tools are looking to create a business model that is effective today, but will also remain effective as the industry grows,” he says.

Depending on their location, greenhouse growers may be able to get by with fewer environmental controls. A ridge vent or a breathable wall can help regulate heat and humidity without the need for additional high-tech cooling systems. But using the proper equipment and materials are crucial for success. Greg Ellis, regional sales director at Nexus Corporation, says galvanized steel framing, rack-and-pinion devices, automated motors and fabric curtains are essential for proper light deprivation.

DIY and Low-Tech Light Dep

Low-tech light dep is the most cost-effective method for extending the growing season, and it’s usually employed by operations that grow cannabis in hoop houses. Aluminum rods, PVC pipe, hardware store plastics and films are tools of the trade for growers that choose a manual blackout system.

Many growers will use so-called “panda plastic” (black on one side, white on the other) to black-out greenhouses. The white exterior reflects sunlight to prevent the structure’s interior from getting too hot.

Every 24 hours, an employee must manually pull the tarp or fabric over the structure to help induce flowering, and then remove it 12 hours later.

This method can be labor intensive, but there are other downsides, too. Growers who don’t live in mild, consistent climates may end up battling the elements. Heavy rainfall or high winds can damage the covering or blow it off the structure altogether.

Some manufacturing companies sell high-end blackout films with multi-year guarantees, but many hardware store plastics won’t last more than one grow cycle. They’re also prone to hot spots and light spillage — problems that can keep plants from flowering properly.

As a general rule, “growers should choose fabrics, not films,” Valdman says. “It allows growers to avoid adding to the landfills, and it allows them to achieve light dep without having a large carbon footprint.”

Still, the DIY option may be ideal for some producers who aren’t looking to compete with the largest commercial greenhouse operations.

“For some growers, the simpler designs, lower costs and ease of hoop house construction are especially appealing,” says Greg Ellis, regional sales director at Nexus Corporation.

Growers who aren’t ready to invest in automatic systems but don’t have the time or crew to manually pull coverings over their structures have options as well. Harvest Excel’s Golden Arm Tarp Puller and Push Rod, for example, attach to any tarp and allows a single person to cover and uncover the structure.

Growers can also install aftermarket shading systems onto many structures. But, Cohen cautions, these systems tend to bunch, causing light spillage or extra shadows because they weren’t designed when the structure was first built. Cohen compares it to putting a Subaru racking system on a Mustang.

“Subarus are designed to have racks from the very beginning; Mustangs are not,” Cohen says. “You can buy one aftermarket and put it on top, but the difference is pretty profound. When things are engineered into the product, they work much better.”



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