It’s been nearly a decade since Washington and Colorado became the first U.S. states to legalize adult-use cannabis—and almost four years since Canada led the way with nationwide legalization. For commercial cultivators, today’s landscape bears little resemblance to those early days. Current trends in commercial cannabis nutrition are very different from when it all began.
Systems Approach to Growing
With the increase in highly controlled growing environments and technological advances, growers are gravitating toward a more holistic, systems-based approach to growing. Horticulturist Shaye Donald and agronomist Jean-Pierre Fortin, members of the professional technical services team at Hawthorne Gardening Company, work directly with commercial growers to help fine-tune growing practices and product use as part of a comprehensive approach.
While cultivators in the past heavily emphasized nutrition, Donald explains that perspectives are changing. Though nutrition remains integral, it’s being seen as part of the broader whole. More growers are focusing on the integrated growing environment, with nutrition being one piece that works in concert with growing media, irrigation, fertigation, and other aspects of the grow.
“Plants, like any living organism, are complex, and so the environment in which they grow isn’t just one piece. It’s a system where they’re all interconnected and affect each other,” Donald says. At Hawthorne, the concept behind this trend is driven home with the Hawthorne 360 initiative. “It’s all about recognizing that this is a system, so we need to take the systems approach to it,” he adds.
Nutrient-Based Crop Steering
Donald shares that crop steering—managing setpoints or inputs throughout the growing process to trigger specific plant responses—is another emerging trend.
“Crop steering is the human aspect of changing these setpoints to get a response that we desire,” he explains.
While growers understand the need for making changes during the crop cycle—from lighting setpoints and fertilization rates to irrigation practices and environmental setpoints such as humidity and temperature—Donald says growers are paying more attention to fine-tuning their setpoints with steering in mind.
“On the nutrient side of things, there’s a lot of different signals we can send to the crop, through different macronutrients especially,” Donald says. By changing nutrient ratios—particularly nitrogen, phosphorus, potassium, calcium, and magnesium—growers can steer plants toward desired responses at different growth stages. One simple example is increasing nitrogen during the vegetative stage to encourage and support leaf and stem growth.
“Then when you move into flowering, you want to provide more of the nutrients for flowering structures and then secondary metabolites,” Donald explains. Hawthorne’s research has focused on refining how to best feed crops to get the responses growers want most.
Irrigation Automation and Management
The importance of irrigation has long been underestimated. But that’s changing as commercial cultivation moves toward precision automation in water and nutrient delivery—vital to optimal crop steering results.
“Trend wise, people are moving more and more towards automation,” Donald says. “A lot of these [crop steering] techniques rely very heavily on automated equipment.” It’s very hard, he adds, to reliably steer crops through hand watering.
Fortin and Donald share that many growers still hand water—especially in new markets. But automated drip irrigation, an integral part of the Hawthorne 360 approach, is on the rise. Coupled with automated fertigation and simpler, more efficient nutrient routines, growers can easily and efficiently change recipes to steer crops and save money.
Automation can run from simple to sophisticated. The most basic level, Fortin says, is simply a timer to trigger irrigation events.
“If we go up in the automation, then we can have soil moisture sensors that will sense the moisture content and some irrigation setpoints will be programmed into the software of that controller,” he explains.
Fortin emphasizes that many problems in commercial grows are related to a lack of uniformity. Automated irrigation and a better, leaner fertilizer program can help. “It’s uniformity in the water, but water is a carrier for nutrition,” he says. “So, it’s also uniformity for the nutrition of the crop—and that adds up.”
Smaller Growing Media Volume
Trends in nutrient-based crop steering and automated drip irrigation tie in heavily with a move toward reduced pot sizes or smaller root zones in commercial cannabis. Automation allows for more frequent watering, which enables growers to reduce pot size and maximize the potential of nutrient-based crop steering techniques.
Fortin explains there are two main avenues to crop steering: “The first one is having a very small container for a very large plant. Obviously, you cannot supply the day’s needs with just one watering, so we have to split watering into several events.” Rockwool cubes are an example of growing media too small to hold enough water to meet an entire day’s demand.
Once automation and smaller root zones are in play, the other route forward is just-in-time nutrition. Instead of watering once a day with all the nutrients the plant needs, nutrients can be delivered throughout the day as a plant needs them. Fortin explains that with the smaller root zone, water carries nutrients closer to the roots, enabling more efficient absorption as well.
The trend toward less growing media volume allows a much greater degree of control, allowing growers to play with what’s commonly referred to as the dry back—typically the time between irrigation events or the degree of dryness allowed before the morning’s first irrigation event.
“I think that’s where things are heading towards now,” Donald says. “The general consensus is that if you have a drier root environment—if the plant kind of detects drought stress—then it will start to send signals up that can have downstream effects. Increasing flower production, for example.”
“I like to think I’m always learning, and I think the best growers are always learning,” Donald adds.
Embracing a systems approach is part of that growth. By considering your entire grow as a system, with all aspects interconnected and working together, you can bring each of these trends in commercial cannabis nutrition to fruition as part of a more productive, more efficient, and more profitable whole.