Question: As profit margins dwindle by the day, my company is constantly searching for improvements and ways to increase our yields without compromising quality. With so many businesses struggling, could you share some ways to increase yield while maintaining quality?
Answer: Keeping in mind there are literally hundreds of parameters that can be tweaked or refined to encourage higher yields while not compromising quality – a whole book could be written on this subject – here are a few, some of which you probably currently employ.
1. Under-Canopy Lighting
Under-canopy lighting is not new. Decades ago, indoor growers employed fluorescent lights under their canopies because they were the only practical light form available.
Today, LED lighting manufacturers have developed lighting specifically designed for under-canopy use. They also make purpose-built, adjustable stands that enable a grower to place the light exactly where it is required. I have friends who have increased the quality of the product while increasing yield by as much as 30%. Under-canopy lighting’s effect on quality comes predominantly from the B- and C-grade buds lower on the branches receiving an increase of light, resulting in fuller, denser buds.
2. Perfect Drying and Curing
By avoiding overdrying buds and focusing on water activity and moisture retention during both drying and curing, growers can better preserve volatile monoterpenes that evaporate at a much lower temperature than water. By maintaining a desirable moisture content and terpene content, you also preserve the weight of the buds, which impacts yield. If a grower preserved just 4 grams per pound in water/terpene weight, and harvested a thousand pounds per month, this water/terpene weight would equate to a sizable increase in yield. Utilize purpose-built curing equipment to prevent unwanted moisture and terpene loss due to evaporation, which ultimately affects final yield.
3. Proper Environments for Trimming and Packaging
Same as above, the unintended loss of both moisture and terpenes in trimming, packaging, and pre-roll environments equates to lost weight. So, control the trimming, packaging, and pre-roll environments to prevent water and terpene evaporation.
4. Vertical/Multi-Level Horticulture
Obvious, yes. But the most logical way to increase yield is to increase the number of plants in whatever space is provided. When you can no longer sprawl horizontally, densify vertically.
5. Nutrient Refinement
Once upon a time, there was no such thing as a nutrient line specifically blended, designed, and tailored to a cannabis plant. Back then, we had to utilize fertilizers with a given N-P-K and refine it with trial and error, combined with the application of supplemental beneficial formulations, be it Cal-Mag, fish emulsion, blackstrap molasses, or a whole host of other amendments. We had to experiment to refine a proper nutrient regimen – even today, I have nutrient application records dating back over 20 years.
Whenever possible, experiment with nutrient refinement and application. Keep accurate yield records of your findings, with the goal of finding the desired sweet spot in nutrient delivery for each cultivar to maximize productivity.
6. Irrigation Strategy/Crop Steering
Crop steering is simply directing a plant's growth toward a specific desired outcome. By precisely controlling environmental and root zone parameters, among others, a grower can “steer” a plant to focus on a specific stage of growth. Likewise, leveraging real-time data from all environmental controls can enable one to make precise adjustments throughout the lifecycle of the plant, from irrigation and nutrient levels to vapor pressure deficit, light intensity, and spectrum. Refining and manipulating these parameters in a grow can exploit plant hormonal responses.
7. Water Oxygenation
Many growers realize the CO2 requirements of their plants’ growth, yet some overlook the oxygen requirements of the root zone. Since a plant's roots absorb nutrients, oxygen, and water, growers must ensure proper oxygen levels are maintained in all irrigation systems.
8. Pathogen Prevention
Start with confirmed virus-free genetics, and regularly get lab testing performed to ensure you are viroid-free. Only introduce new genetics after they have a clean bill of health, as plants infected with a virus (like hop latent viroid) inevitably begin to yield less over time.
9. Proper CO2 Levels
Plants prefer a CO2-rich environment. CO2 is utilized to increase photosynthesis, which encourages rapid growth in larger yields. Some growers today only utilize ambient CO2 levels (around 425 ppm), but CO2 enrichment can increase the efficiency of photosynthesis by as much as 30% in a sealed environment. Cannabis plants prefer a range between 800 and 1,500 ppm, depending on growth stage.
10. Proper pH Levels
Many growers record the pH of their irrigation water when it is applied, but few measure and record the pH of their wastewater after it filters through the substrate. This information can inform growers on whether there is a nutrient buildup, which causes nutrient lockout or unavailability. Growers typically aim for a 10% nutrient runoff rate to prevent such buildup.
11. Optimize Light Intensity and Spectrum
For the last few years, academics and lighting manufacturers have been researching the exact spectrum preferences of a flowering cannabis plant. Findings show each cultivar has its own spectrum preferences. Therefore, it is best to purchase lighting with the ability to adjust spectral output, which allows a grower to dial in the desired spectrum.
As for light intensity, dimmable fixtures will help maximize light as plants mature. Also, position fixtures as close to the canopy as possible without adversely affecting leaf surface temperature.
12. Genetic Selection
Not all seeds are created equally, meaning some seeds of a given cultivar will yield more, and some will yield less. If your chosen cultivars yield less than desired, perhaps investigate alternative sources of the same chemotype in the hopes that one of the phenotype differences is an increase in yield without a compromise in desired quality.
13. Defoliation and Pruning
The only practical method to get light to penetrate the top canopy to the lower buds is to strategically remove plant material. You also must periodically remove lower vegetation that does not receive adequate light, so remove lower leaves and branches that do not get proper lighting (and will result in airy, fluffy buds anyway). By removing this unusable material, you redirect the plant’s energy to the remaining foliage. To encourage light penetration, remove lackluster, older fan leaves, and larger fan leaves that prevent light penetration to the lower branches and buds. The result will be heavier and denser buds.
14. Training, Fimming, Topping, and SCROG
Some growers prefer to utilize fewer, larger plants that are spread out and occupy a larger space. This is achieved by training the branches to spread out horizontally rather than vertically via a trellis (called a “screen of green” or “SCROG”). Some top the plants to encourage lateral branch elongation, which is encouraged by training to form a larger canopy. Regardless of the method, the purpose is to make the plant occupy a larger space and fill it up to maximize bud sites, resulting in a larger yield per plant.
15. Harvest at Peak, Not by Calendar
Only harvest when each cultivar is at peak ripeness for a given compound or output. For example, some material destined for extraction is harvested slightly early to ensure that trichome heads haven't oxidized and begun to darken in color, which would produce a darker colored extract. A bud that is harvested at peak potency will yield more weight than an immature or overripe bud will.
Kenneth Morrow is an award-winning grower and breeder. He is the owner of Trichome Technologies, a research and development company. He is also a consultant and author of the book "Marijuana Horticulture Fundamentals" and a founding advisory board member of Cannabis Business Times, where he has been a columnist since 2015. Find him on Instagram @trichometechnologies or reach him via email at: [email protected].
