Tag Archives: light

photo of outdoor grow operation

How to Reduce Mold & Contaminants in Indoor, Greenhouse and Outdoor Grows

By Ketch DeGabrielle
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photo of outdoor grow operation

Controlling your grow environment doesn’t start when you germinate your first seeds, it starts before you build your grow. There are steps you can take that will have a significant impact on mold growth and contamination, and these will vary based on the grow environment you choose.

Below is a roadmap to where each grow environment stands in terms of mold and contamination risk, and simple steps you can take to mitigate these factors.

Outdoor

The benefits of an outdoor grow are significant – using natural sunlight to grow plants is both inexpensive and environmentally sound. However, it allows the least amount of control and makes plants susceptible to weather conditions and outdoor contaminants including dust, wind, rain and insects. Depending on humidity and precipitation levels, mold can be a big issue as well.

Outdoor growing has obvious benefits, such as natural sunlight, but may also require extra steps to prevent contamination

When selecting an outdoor area for a cannabis farm, there are two important factors to consider: location and neighboring farmland. Geographical environments and sub-climates vary and once you have purchased land, you are committed, so be sure to consider these factors prior to purchase.

While arid desert climates have abundant sunlight and long growing seasons, flat, dry lands are subject to dust-storms, flash floods and exceedingly high winds that can damage crops. Conversely, more protected areas often have high humidity and rainfall late in the season, which can create huge issues with bud rot and mold. Neighboring farms also have an impact on your grow, so be sure to find out what they cultivate, what they spray, their harvest schedule and how they run their operation. Large farming equipment kicks up a lot of contaminant-laden dust and can damage crops by displacing insects to your farm if they harvest before you. Pesticide drift is also a major issue as even tiny amounts from a neighbor’s farm can cause your crops to fail testing, depending on what state you are in.

With outdoor grow environments always at the mercy of Mother Nature, any cultivator is wise to control contamination potential on the ground. Cover soil and protect your crop by planting cover crops and laying plastic mulch on as much ground as reasonable. In many cases it makes sense to irrigate uncultivated parts of your farm just to keep dust down.

Greenhouse

Greenhouses are the future of cannabis cultivation. They allow growers to capture the full spectrum and power of the sun while lessening environmental impact and operating expenses, while still being able to precisely control the environment to grow great cannabis. With recent advancements in greenhouse technology such as automated control systems, positive pressure, geothermal heating or cooling and LED supplemental lighting, greenhouses are the future. However, older or economy greenhouses that take in unfiltered air from outside still have a medium amount of mold and contamination risk.

A greenhouse grow facility

Before building your greenhouse, study the area while taking into account climate, weather conditions and sun exposure. Excessively windy areas can blow in contaminants, and extremely hot climates make cooling the greenhouse interior a challenging and costly endeavor.

There are several simple operational tactics to reduce contaminants in a greenhouse. Add a thrip screen to keep insects out, thoroughly clean pad walls with an oxidizing agent after each cycle, and keep plants at least 10 feet from pad walls. Plan to flip the entire greenhouse at once so that you can clean the greenhouse top to bottom before your next crop. A continuous harvest in your greenhouse allows contaminants to jump from one plant to the next and reduces the ability to control your environment and eliminate problems at the end of a cycle. Lastly, open shade curtains slowly in the morning. This prevents temperature inversion and condensation, which can cause water drops to fall from the ceiling and transfer contaminants onto plants below.

Indoor

An indoor environment offers ultimate control to any grow operation. Cultivators can grow high-quality cannabis with the smallest potential for yeast and mold growth. Unfortunately, indoor environments are extremely expensive, inefficient and environmentally costly.

Talltrees
An indoor cannabis operation set up (Image: Tall Trees LED Company)

With indoor grow environments, keeping mold and contaminants at bay comes down to following a regimented plan that keeps all grow aspects clean and in order. To keep your grow environment clean, change HVAC filters multiple times a month. It’s also important to install HEPA filters and UV lights in HVAC systems to further reduce contamination threats. Clearly mark air returns if they are near the ground and keep those areas free of clutter. They are the lungs of your grow. Also, stop using brooms in the grow space. They stir up a lot of contaminants that have settled to the floor. Instead, use HEPA filter backpack vacuums or install a central vacuum system. Set up a “dirty room” for anything messy on a separate HVAC system, and be sure to thoroughly clean pots after every harvest cycle.

Learn more about reducing mold and contaminants in an indoor or greenhouse grow in another article from our series: 10 Ways to Reduce Mold in Your Grow.

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Cannabis and the Environment: Navigating the Interplay Between Genetics and Transcriptomics

By Dr. Zacariah Hildenbrand
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It is that time of year where the holidays afford us an opportunity for rest, recuperation and introspection. Becoming a new father to a healthy baby girl and having the privilege to make a living as a scientist, fills me with an immeasurable sense of appreciation and indebtedness. I’ve also been extremely fortunate this year to spend significant time with world-renowned cannabis experts, such as Christian West, Adam Jacques and Elton Prince, whom have shared with me a tremendous wealth of their knowledge about cannabis cultivation and the development of unique cannabis genetics. Neither of these gentlemen have formal scientific training in plant genetics; however, through decades of experimentation, observation and implementation, they’ve very elegantly used alchemy and the principles of Mendelian genetics to push the boundaries of cannabis genetics, ultimately modulating the expression of specific cannabinoids and terpenes. Hearing of their successes (and failures) has triggered significant wonderment and curiosity with respect to what can be done beyond the genetic level to keep pushing the equilibrium in this new frontier of medicine.

Lighting conditions can greatly impact the expression of terpenes (and cannabinoids) in cannabis.Of course genetics are the foundation for the production of premium cannabis. Without the proper genetic code, one cannot expect the cannabis plant to express the target constituents of interest. However, what happens when you have an elite genetic code, the holy grail of cannabis nucleotides if you will, and yet your plant does not produce the therapeutic compounds that you want and/or that are reflective of that elite genetic code? This ‘loss in translation’ can be explained by transcriptomics, and more specifically, epigenetics. In order for the genetic code (DNA) to be expressed as a gene product (RNA), it must be transcribed, a process that is modulated by epigenetic processes like DNA methylation and histone modification. In other words, the methylation of the genetic code can dictate whether or not a particular segment of DNA is transcribed into RNA, and ultimately expressed in the plant. To put this into context, if the DNA code for the enzyme THCA synthase is epigenetically silenced, then no THCA synthase is produced, your cannabis cannot convert CBGA into THCA, and now you have hemp that is devoid of THC.So what is the best lighting technology to enhance the expression of terpenes? 

With all of that being said, how do we ensure that our plants thrive under favorable epigenetic conditions? The answer is the environment; and the expression of terpenes is an ideal indicator of favorable environmental conditions. While amazing anti-inflammatories, anti-oxidants and metabolic regulators for humans, terpenes are also extremely powerful anti-microbial agents that act as a robust a line of defense for the plant against bacteria and pests. So, if the threat of microbes can induce the expression of terpenes, then what about other environmental factors? I am of the opinion that the combination of increased exposure to bacteria and natural sunlight enhances the expression of terpenes in outdoor-grown cannabis compared to indoor-grown cannabis. This is strictly my opinion based off of my own qualitative observations, but the point being is that lighting conditions can greatly impact the expression of terpenes (and cannabinoids) in cannabis.

A plant in flowering under an LED fixture

So what is the best lighting technology to enhance the expression of terpenes? Do I use full spectrum lighting or specific frequencies? The answer to these questions is that we don’t fully know at this point. Thanks to the McCree curve we have a fundamental understanding of the various frequencies within the visible light spectrum (400-700nm) that are beneficial to plants, also known as Photosynthetically Active Radiation (PAR). However, little-to-no research has been conducted to determine the impacts that the rest of the electromagnetic spectrum (also categorized as ‘light’) may have on plants. As such, we do not know with 100% certainty what frequencies should be applied, and at what times in the growth cycle, to completely optimize terpene concentrations. This is not to disparage the lighting professionals out there that have significant expertise in this field; however, I’m calling for the execution of peer-reviewed experiments that would transcend the boundaries of company white papers and anecdotal claims. In my opinion, this lack of environmental data provides a real opportunity for the cannabis industry to initiate the required collaborations between cannabis geneticists, technology companies and environmental scientists. This is one field of research that I wish to pursue with tenacity and I also welcome other interested parties to join me in this data quest. Together we can better understand the environmental factors, such as lighting, that are acting as the molecular light switches at the interface of genetics and transcriptomics in cannabis.

The Great LED Debate

By Aaron G. Biros
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The preferred choice for indoor cannabis growing has long been high-pressure sodium (HPS) 1000-watt light bulbs during flowering. Light-emitting diodes (LED) are quickly changing the indoor farming landscape with innovative technologies and promising energy savings. Many think the technology still needs time to develop. There are certainly many pros and cons to switching an indoor cultivation facility from HPS to LED lighting systems.

Steve Kruss, president of Light-Waves Electronics, Inc., gave a comprehensive analysis of the advantages and disadvantages of various light sources at the CannaGrow Conference and Expo. “The first adopters [of LED light technology] more than two years ago did not get the results they wanted, so many growers gave them a bad rap very early on,” says Kruss. His discussion delved into the pros and cons of both LED and HPS lights in growing cannabis.

lightwavesinc
Light-Waves Electronics Inc. LED fixtures being installed in a cultivation facility.

It is important to highlight the weaknesses in many common HPS systems and the possible solutions that LED technology could offer. According to Kruss, HPS lights do not match the light spectrum’s photosynthesis curve that plants need to absorb energy. HPS lights give off a tremendous amount of heat that requires more energy to cool a facility down with an HVAC system, increasing energy costs for growers. Since LED’s use 50% less wattage, they produce approximately 50% less heat, significantly reducing cooling costs. HPS light bulbs need to be replaced multiple times per year. Quality LED fixtures can last more than 50,000 hours, or roughly eleven years. “The reality is HPS is putting a lot of light out but that energy is wasted because so much of it is in a light spectrum that plants do not absorb,” says Kruss. Perhaps most important is the lack of ability to vary the light spectrum; any light that HPS bulbs produce that the plant does not absorb is essentially wasted energy.

LED light bulbs provide a solution to the wasted light in HPS by targeting the particular spectrum that plants need for photosynthesis. By targeting the photosynthetically active radiation (PAR), roughly 400-700nm, LEDs can effectively mimic the sun’s ability to produce the wavelength of light specifically needed in a certain stage of cultivation. The absorption spectra and action spectra are wavelengths of light preferable for harvest as well as plant growth and metabolism, respectively. LED manufacturers and growers commonly try to harness the Emerson Effect, which uses red (670nm) and far red (700nm) to increase the rate of photosynthesis.

A plant in flowering under a Light-Waves Electronics LED fixture
A plant in flowering under a Light-Waves Electronics LED fixture

The benefits of LED lights in growing cannabis are numerous. The primary benefit is that it provides light at the specific wavelengths chosen to match the specific needs of plants. When finely tuned, LEDs can influence the growth process by slowing down vegetative plant growth and inducing flowering when appropriate. LEDs are more energy efficient than their counterparts partially because they give off substantially less heat in the beam itself, reducing cooling costs. Some growers use LEDs together with HPS lights, some use LEDs with natural sunlight in a greenhouse setting and some use strictly LEDs for the entire growth cycle. Each cultivation operation has its own budgetary restraints and structural limitations, but energy efficiency is one area that all growers should look to improve. According to Adam Koh, chief cultivation officer of Comprehensive Cannabis Consulting (3C), indoor growers can get away with T5 fluorescent lamps (which do not consume much energy) throughout the vegetative process.

For some, the debate is over and growers recognize the added benefits that LEDs bring to growing cannabis. According to Kruss, LED technology is almost there. “In terms of yields, LED lights are providing around 75% of the weight that HPS produces, but on the vegetative side, the growth is considerably faster which could make up for that weight loss with faster grow cycles and an extra harvest,” says Kruss.

Talltrees
An LED cultivation operation set up by Tall Trees LED Company

Adam Jacques, award-winning grower and founder of Growers’ Guild Gardens, has used LEDs in tandem with sunlight. Him and his team have bred and grown cannabis in indoor, greenhouse and outdoor operations. “I love the huge steps that some LED manufacturers have made in the past year,” says Jacques. “When I utilize them within a greenhouse setting I really like the product it grows.” Jacques’ findings in the field echo Kruss’ statements that LED lights have made considerable progress very recently. “It does take a little dialing in due to the plants’ increased feeding regiment, but it is a small price to pay for all of the benefits we see,” adds Jacques. His success with the new technology is representative of a larger trend; more and more growers are beginning to implement LEDs in some form.

Some claim the yield is less from LED lights during flowering.
Some claim the yield is less from LED lights during flowering.

Maxx Wiley and Robert Manes, co-founders of Tall Trees LED Company based in Arizona, believe their technology is on par with the yields other growers are getting with different light sources. “We conducted heads-up tests with our 500-watt LEDs versus other 1000-watt HPS bulbs and have seen very impressive results,” says Wiley. “The plants under our lights were consistently getting more weight and more flowers; the flowers appeared smaller but were actually denser and heavier in reality.” Wiley’s company makes commercial LED luminaires that are IP 65 waterproof rated and he claims they never had any issues with failures. The technology uses no moving parts to cool the lights, just metal clad circuit boards, heat sinks and conductive thermal-bonding materials. “We have had customers run potency analyses and have found tremendous variation in plants grown with HPS,” says Wiley. “We see more compound production and more consistency crop-to-crop with our LED technology.” There are currently a handful of manufacturers bringing innovative designs to market.

A cultivation operation in Maine using GS Thermal Solution liquid-cooled LED fixtures
A cultivation operation in Maine using GS Thermal Solution liquid-cooled LED fixtures

GS Thermal Solutions, based in Connecticut, manufactures 1000-watt LED fixtures that are liquid-cooled. The company makes lights that are fully adjustable, so growers can dial in each spectrum of light intensity independently and tailor to specific strains as well as stages of growth. According to Rick Rhyins, vice president of sales at GS Thermal Solutions, the liquid cooling technology allows for a much longer lifetime of the LED and a much more efficient energy consumption. “Our technology addresses the shortcomings and previous problems with early generation LED models,” says Rhyins. Coupled with facility automation, GS Thermal Solutions uses a central control system to monitor cooling, light intensity and spectra, nutrient monitoring and feed control.

Yet some are still skeptical of the LED lighting in today’s market and feel the technology is not there yet. Nic Easley, chief executive officer of Comprehensive Cannabis Consulting (3C), has brought over sixty cultivation operations to market and is hesitant to endorse the technology at this point. “I will never be an early adopter when it comes to new lighting technology and I feel we are at least a year out from seeing consistently efficient LED lighting,” says Easley. “There are still a lot of false claims out there and I want to wait until I see repeatable results on a small scale before I feel comfortable endorsing LED lights for cannabis cultivation.” While companies will continue to innovate lighting solutions for indoor cultivation, in many cases (but not all) it seems using the sun to grow cannabis would be more energy efficient.