Harvest factors in the daily light integral (DLI) in its greenhouse operations to be sure plants get the optimal amount of light year-round.
Photo Courtesy of Fluence

Editor's note: This article has been updated with the accurate number of cultivation sites Harvest operates.

Harvest Health & Recreation operates eight cultivation sites and is constructing three more with opening dates planned for 2020. That cross-country experience has taught the vertically integrated, multi-state operator based in Arizona that establishing growing and processing facilities in multiple locations is never a one-size-fits-all process when working with live plants.

Each Harvest indoor operation, greenhouse or outdoor grow requires different cultivation parameters to grow the best quality cannabis in the most efficient way, especially considering it is producing plants in climates as varied as Florida and Ohio.

Lighting is one of the most important aspects of a successful operation, and decisions are made carefully and early in the planning process.

When preparing a cultivation site in a new state, Harvest must first review the state regulations to determine what is possible, as some dictate the facility type, says Egan O’Keefe, eastern regional cultivation manager for Harvest. After that, the company considers the purpose and the location of each facility to determine lighting needs and what the daily lighting integrals (DLI) are, he adds.

DLI, an accumulation reading of how much photosynthetically active radiation (PAR) light a plant has received within an entire photoperiod, is most often a factor in greenhouses, where additional lighting is needed to supplement natural sunlight and compensate for when it’s cloudy or when the days are shorter.

For example, Harvest currently is building a greenhouse in Maryland, O’Keefe says. To gain the most efficiency, the greenhouse is angled to maximize the amount of natural light hitting the glass roof “every single minute of the day,” he says. But that’s not enough.

“Obviously we’re not working with the [full sun year-round], so we are going to look at the most energy efficient, but also [the most] advanced technology that we can utilize within the facility to optimize and replicate sunlight indoors” without being wasteful with energy, O’Keefe says. “Both of those are our big factors for determining our fixtures.”

Harvest uses systems with photometric sensors that automatically cue lights at specific intensities so that optimal light conditions are maintained consistently without turning “the greenhouse operation into an indoor operation,” O’Keefe says. DLI is a major part of that calculation.

“In Palm Springs, Calif., the DLI is incredible, and we only have to utilize our interruption light for a few hours in the evening and early morning. We use very low energy and are very cost efficient in those regions, versus in Ohio, we constantly have to run LED lights, and the signal sensors turn the interruption lighting on to maintain what we are trying to achieve while we have that significant cloud cover or rain,” O’Keefe says.

That’s why installing energy-efficient but powerful fixtures is crucial for Harvest’s success. Since O’Keefe started working with the company four years ago, he has seen major advancements in lighting technology that have made a big impact on yield, cannabinoid profile quality and potency.

“There are outstanding products on the market, and now there are some exceptional companies building custom lighting fixtures to the request of the cultivator or the needs of the environment, between design and the makeup of these facilities and greenhouses,” O’Keefe says. “LEDs are winning the race for the most optimal and efficient lighting method.

“There has been LED technology for a long time, but not [tailored to] ... cannabis production,” he continues. “All of that is taken into consideration and then put into the design of the new fixtures.”

O’Keefe says lower-wattage fixtures and a much higher-quality lighting spectrum have been the most significant developments, as they have allowed the company to be more energy conscious and save money. He advises cultivators to keep up with the latest lighting research and technology available.

“If we use the latest and greatest, most efficient lighting methods, we can gain rebates from energy companies by being very efficient in the design of these huge commercial facilities,” he says. “Lean on the advancements in technology while considering standard agriculture practices at the same time, and [know] that geographic location and DLI are the most important factors."

Michelle Simakis is editor of Cannabis Business Times and sister publication Cannabis Dispensary magazine.