Why robots just can't grow good weed

From the robots that fail miserably at their jobs to the robots dealing with our literal crap, Mashable’s Crappy Robots dives into the complex world of automation — for better or worse or much, much worse. 

Cannabis farm production is at an all-time high, but it's unlikely that robots will take over the process anytime soon.

The stereotypical weed farm is either a sprawling expanse of crop tended to by free-spirited stoners, or a clandestine basement operation built on information gleaned from online forums. Modern cannabis farm facilities, with their climate-controlled grow rooms and automatic irrigation techniques, are a stark departure from pop culture's preconceived notions of what a weed farm looks like. Though far more clinical than its cliché predecessor, the modern cannabis farm still does the bulk of cultivation by hand. Few, if any, other agricultural spaces use human labor over that of a machine's to the degree that cannabis farms do, but the quality-driven nature of weed requires fine motor skills and age-old intuition that technology hasn't adapted to yet. 

While the agricultural industry has relied on machinery for centuries, automation falls short in the cannabis sphere. The rise in states legalizing marijuana and the 2018 Farm Bill that legalized hemp ushered in a "green rush" of farmers who could grow cannabis, and consumers who could finally buy it. Despite the growing demand, high-quality bud is a fragile crop, and machinery used in conventional agriculture isn't gentle enough to handle it. 

Outdoor farming is limited to areas with consistent sunlight and temperate climates, so most brands farm their weed indoors. Marijuana Business Daily reported that in 2018, more than 80 percent of California's recreational marijuana production capacity was from indoor facilities. But even indoor facilities, unencumbered by outdoor farming's natural limits and boosted by modern technology, require people to do a majority of the work. That isn't because the technology or machinery doesn't exist, but because a trained human being just does the job better than a robot. Agricultural technology may be leaps and bounds ahead of at-home grows 20 years ago, but reaching a Monsanto-level scale of operations is out of the picture for cannabis farms. For now, ensuring high-quality bud still requires significant human involvement. 

"TL;DR: It is easy to do. It is difficult to do well."

"Is marijuana really that difficult, fickle a plant to grow?" one Reddit user asked r/microgrowery, a subreddit for at-home cultivation. "I've never taken up the task, but I do a fair bit of gardening/growing plants/trees as a hobby in the backyard. I'm a fairly laissez-faire grower, and operate mostly on instinct and eyeballs and general knowledge. And I'm fairly successful. But in here, I see so much concern about pH balances, plant nutrients, pesticides, and lighting cycles that it kind of blows my mind. Why all the fuss? Is it because the plant is culturally rooted in a profit-per-growth equation?" 

Another Reddit user summed it up: "TL;DR: It is easy to do. It is difficult to do well." 

Good weed is hard to grow at a large scale

Even if arrogant, the original poster's quip about potential profit was on the money. Craft cannabis farms are hesitant to employ machinery used by industrialized agricultural giants because of weed's high investment, high profit nature. Conventional crops, like tomatoes, also require a controlled environment, thorough monitoring, and careful harvesting. Losing a few pounds of crop to disease, failure to grow, or damage during harvesting is expected. In a plant as costly and labor intensive as cannabis, however, those few pounds can cost a farm tens of thousands of dollars and months of labor. 

Growing weed isn't too difficult. Growing good weed is.

Brett Feldman, co-founder of the eponymous cannabis brand Wonderbrett and long time grower, said quality weed is in such high demand because it's scarce. Growing cannabis is difficult, and growing weed that yields an enjoyable experience for the consumer is even more so — especially at the scale of a large farm. 

"Quality isn't easy," Feldman told Mashable recently during a tour of Wonderbrett's 180,000 square foot indoor grow facility in Long Beach, California. The facility boasts an impressive 36 grow rooms, each containing various strains in different stages of growth. Each room is monitored, irrigated, and tended to through a combination of new tech and traditional hands-on work.

"It's expensive, it's hard, [and] even with the people with the best intentions going out to try and do everything they can, they can miss for several years on trying to create something of quality," Feldman continued. 

High-quality weed is in higher demand as states legalize recreational marijuana. Before the days of legal weed, options were limited; nobody asked their dealer what terpenes were in their product. As of April 2021, 17 states and Washington, D.C. legalized marijuana, bringing fresh competition to the market, and exposing consumers better weed. 

He likens good bud to eating McDonald's for your entire life, and then trying a good burger. 

Cameron Damwijk, Wonderbrett's co-founder and engineer behind much of the facility's systems, added that most consumers didn't know how good higher quality cannabis could be until they try it. He likens good bud to eating McDonald's for your entire life, and then trying a good burger. You don't have to be a connoisseur to understand the difference between the dime bag you got in high school and the flower you can buy at dispensaries today. 

"And you're like, 'Well that's a good burger, I was eating [this] burger but that one's better. Now I know the next level of quality,'" Damwijk said. "And then it's...someone being able to see past that and go, 'I do notice that terpene or I do notice that smoothness.'"

Cannabis, for the most part, isn't especially difficult to grow. Dr. Anne Lacey Samuels, a botany professor at the University of British Columbia who researches cannabis structure, noted that low-THC hemp thrives naturally in the prairies. In an email to Mashable, she explained that the plant itself is pretty hardy. 

Growing high-THC, smokable flower is more challenging. It's a juggling act that involves genetics, thorough monitoring, and careful harvesting that all revolve around cultivating a mature plant's flower, colloquially known as bud. The gnarled, earthy nugget may not look like much, but its color, aroma, and texture affect the user's experience consuming whatever weed product the bud ends up in. From the live resin in dab rigs to the gummies you might pop before bed, all weed products start out as a sticky little bud. 

Shawn Lucas, an assistant professor of organic agriculture and hemp specialist at Kentucky State University, told Civil Eats that cannabis farming takes an understanding of horticulture beyond basic gardening. 

"If you're going without [an understanding of] basic biology and good quality soil, you'll be in trouble," he said.

Sometimes robots are less efficient than people

The process of growing weed can take 10 to 32 weeks for the plant to fully mature for harvesting. Growers can start from either a seed, or if they have an already mature plant, a cutting called a clone. Clones ensure a quicker growing process than germinating a seed, but they're also fragile because they're still developing roots to soak up nutrients. Aggressive handling or removing the clone from a temperate, humid environment could kill it before it roots, so indoor facilities still water them by hand. The robotic dexterity to handle a clone without damaging it may exist, but it's not accessible or cost effective when compared to a trained person. 

A worker waters delicate clones by hand.

Growers also have to be vigilant about protecting plants from pests, viruses, and mold — Wonderbrett requires anyone entering the facility to walk through an air-blasting decontamination room — as decontaminating the plants themselves can affect the crop. Gassing a grow room with ozone or hydrogen peroxide to rid it of mold, for example, can not only brown the surface of the plants and affect its taste and potency, but also puts employees at risk of inhaling toxic fumes. Another decontaminating technique called radiofrequency uses radio waves to generate heat to kill microbes, but it can also burn the flower. To prevent taking measures as drastic as those decontamination methods, a grower could simply visually assess the plant and nip issues in the bud (literally) before it gets out of hand.

 In theory, one could design a machine learning program to catch potential issues early on, but again, that's not as accessible or cost effective as a trained eye. 

Enhancing the growing process 

There are elements of the indoor growing process that have been enhanced by some level of automation. The uptick in newly legalized home grows also created a demand for personal automated climate control systems; Green Goddess Supply sells furniture-like grow boxes called "The Armoire" that include timed LED lights, a temperature and humidity reader, ventilation fans, and a WiFi connected camera to monitor the plant's growth for $1,495. Cultivation startup Grobo takes the souped up grow tent even further by automatically watering and fertilizing the plant within — for $2,299, home growers just have to drain the closet's tank once a week, refill it with fresh water, and let the closet automate the rest. 

At a farming scale, it's not as simple as planting a seed in a box and occasionally checking in via app, but modern farming systems use the same concept. The room's humidity, carbon dioxide levels, hours of light exposure, airflow, and nutrients administered all affect the weed's quality. Seemingly innocuous hiccups like a dip in temperature or too few hours of light can stunt the plant's ability to produce prized buds, so indoor grow facilities opt for automatic systems that can time light cycles and regulate the climate. 

When I visited Wonderbrett, for example, leaving the door open for a hair too long triggered the room's system to automatically release more carbon dioxide. Each room had its own set of meters to monitor humidity, temperature, and carbon dioxide, and a change from the ideal threshold would trigger the system to correct it. Damwijk noted that having a record of humidity, temperature, and carbon dioxide levels has been helpful in playing with the formula to improve each harvest. Still, those levels have to be manually adjusted every few weeks throughout the grow cycle, instead of automatically adjusting to preset stats. Damwijk doesn't know of any software that would allow growers to plan out a humidity, temperature, and carbon dioxide adjustments for a whole grow cycle, for multiple grows concurrently.

"In the past, even when you were just going in visually inspecting, you didn't know what was going on at two in the morning...you just took a leap of faith."

"In the past, even when you were just going in visually inspecting, you didn't know what was going on at two in the morning...you just took a leap of faith that it was all going to be good the next day and you roll the dice," Damwijk said. "But now you get to see through this data that you get to look at, all these things that go into it, working together in a kind of symbiotic relationship."

Irrigation can also be automated to some degree, though effectiveness varies based on technique and the farm's size. Methods that work for small-scale home grows, like using "Bubbleponics" to grow roots in a reservoir aerated by an aquarium pump, are inefficient or too risky for larger scale farms. Arizona-based cannabis brand Aeriz grows at scale using an aeroponic system, in which plants are suspended mid-air and watered by automatically misting their exposed roots with nutrients. Aeroponic systems are known to yield high-quality bud without soil or pests, but can be prohibitively expensive and because the fragile roots must stay moist at all times, run the risk of killing the plant if automation fails and the roots dry out.

Most farms opt to use drip irrigation, which gradually sends water to the roots of the plant at a low pressure and low volume. Companies that specialize in irrigation systems often offer "fertigation" services — a portmanteau of irrigation and fertilization — that automatically disperse nutrients in the water used for drip irrigation for both conventional crops and cannabis grows. Used in conjunction with an automated control system, is (or should be, at least) a breeze. 

There isn't a one size fits all cultivation system, which revolves around growing strains unique to the brand, so farms tweak stock systems to their needs. Conventional agriculture may face similar issues in tailoring farming practices to different crops, but it's unlikely that it's to the degree that cannabis farms do for their various strains. 

Take the tomato: there are plenty of breeds, from the staple Roma to the enviable Brandywine Heirloom. They both have their own distinct flavor that distinguishes them from each other, but at the end of the day, both can be grown in the same garden without greatly affecting your tomato-eating experience. Different strains of weed, on the other hand, grow best in varying conditions; the indica Blue Dream can take high amounts of nitrogen without its roots burning, whereas the high-CBD yielding ACDC is notoriously sensitive to nutrients. 

Damwijk and Feldman couldn't find a stock system that would individually irrigate all 36 grow rooms with the nutrients they wanted to use without clogging up the delivery hoses, so Damwijk designed and engineered one himself. All of the veins pumping throughout the facility convene in one room, where a lattice of 36 metal pipes are programed to draw nutrients from the handful of massive vats towering over attendants. For each room with different strains in varying stages of growth, this vascular network delivers a specific blend of nutrients in varying concentrations. To encourage robust root growth in younger plants, a six inch by six inch plastic cap covers the base of the plant's stem. Rather than pooling in one spot, the irrigation system evenly distributes water and nutrients to all four corners of the plant's base via channels carved into the cap. That way, the young plant's roots are encouraged to spread out as far as possible through the fiberglass-like cube encasing it, which will make it a stronger adult plant. Damwijk explained that Wonderbrett's irrigation system is "nothing completely different that the industry is not doing," but a modified version of what already exists. 

"This was our main kind of innovative piece that we had to make for ourselves to keep growing the way that we wanted to grow," he said.

Where human and machine can work together

The most laborious step in cultivation is trimming. Once the plant is ready for harvest, the hair-like strands covering the bud called stigma will turn orange, and the crystalline structures encircling it called trichomes will develop an amber hue. Provided that the plant makes it to that stage, growers can finally harvest it by hanging stems to dry for a few days before trimming off each bud and then curing them for consumption. In the wild, those sticky trichomes act as the plant's defense because its smell deters predators from snacking on it. For us humans, those smelly trichomes are exactly what we want in good weed.

Hand trimming, a laborious and often low-paying task, preserves more of the bud's quality than machine tumbling does.

"The trichomes on the flowers are critically important, because they are the part of the plant that produce the cannabinoids (THC or CBD) and terpenoids," Lacey Samuels said. 

Those cannabinoids interact with receptors throughout the body to produce therapeutic effects. THC, for example, is known for its psychoactive euphoric "high," while the increasingly popular CBD may impact sleep, anxiety, and inflammation. Products boasting lesser known cannabinoids like CBN and CBG are also on the rise, but more research is needed to draw concrete conclusions on their effects. Terpenes are the compound that give all plants their smell and taste, and in marijuana, drive the "type" of high each strain might yield. 

For instance a citrus-forward strain might contain limonene, known for creative and uplifting highs, whereas the muskier myrcene is known for its sedative, analgesic effects. Many couch-locked nights can be attributed to the humble myrcene. 

Preserving those trichomes is crucial in the drying and harvesting process because it's where all the good stuff is, which is why craft farms opt to buck and trim stems by hand. Bucking involves removing each bud from the stem before meticulously trimming remaining leaves and other unwanted plant matter from the trichome-encrusted bud. Trimmers may save certain parts like sugar leaves, which contain trichomes but aren't as flavorful or potent, to use in pre-roll joints or extracts. It's a tedious process by hand — Feldman estimates that a trained worker can trim about a pound and a half of bud during an eight-hour shift. 

Bucking and trimming equipment exponentially speeds up the process, but current machinery can be rough on the delicate buds and slough off the desired trichomes. Bucking machines like the Mother Bucker or the MBX Bucker can buck 150 pounds of bud per hour by feeding wet or dry stems through a small hole so that the buds pop off for collection. Trimming machinery like Twister Trimmer's or the Triminator tumble dried buds in a rotating perforated cylinder so leftover leaves are ripped off. Twister Trimmer claims its largest model can trim 600 pounds of bud per hour, and that its most used commercial model can trim 14 pounds of dry bud per hour. The Triminator boasts a trimming rate of 60 pounds per hour. 

While those rates outshine any human's hand trimming, weed purists believe machine trimming cheapens the bud by damaging its trichomes, which makes the product less aromatic and less potent. To avoid loss, growers could use the loose leftover from a machine trim for shake, but traditionalists see hand trimming as an art in itself. Bloom Automation, a robotics company based in Massachusetts, seeks to bridge the gap between the laborious finesse of hand trimming and machine trimming's crude efficiency with artificial intelligence. 

Jon Gowa, Bloom Automation's founder and CEO, saw a need for more delicate automation while working in agricultural robotics while working with "very low value" crops like rose bushes.

"Cannabis crop is very, very expensive to produce but certainly expensive to purchase as a consumer," Gowa told Mashable. "As opposed to the Bud Lite of the industry, they're looking for those craft beers [that] are the really nice cannabis strains...It's an expensive investment every time they purchase the product."

Bloom Automation's trimming system uses machine learning to capture images of leaves and other undesirable plant matter, identify what to keep and what to remove, and then meticulously trims away the excess. His team trained an algorithm with 10,000 images of marijuana, categorizing them into bud, sugar leaves, fan leaves, stems, and branches. They applied another algorithm on top of that one to train it to "vacuum" up sugar leaves and fan leaves, the latter of which can be saved for edibles, tinctures, or hash. Gowa said it identifies and removes unwanted plant matter at 97 percent accuracy, and it can be trained to adapt to different strains. He estimates it's about twice as efficient as a hand trimmer, which lags behind standard trimming machines but preserves more quality. A Bloom Automation machine costs upwards of $20,000. In comparison, Twister Trimmer's most popular commercial model and the Triminator cost roughly $17,000 and $13,800, respectively. Granted, neither operate with a fraction of the precision Bloom Automation's machine does, and all three systems are still more efficient than a hand trimmer. 

Gowa said Bloom Automation's goal — and in a more altruistic world, the goal of automation overall — isn't to replace humans but to replace "dull, dirty, or dangerous" jobs with better ones. He doesn't see automation taking the place of botanists or maintenance workers, but of tedious low-wage jobs. Trimming tends to be the lowest paid gig in the industry, paying either minimum wage or a few hundred dollars per pound. In California, the average trimming wage is about $16 per hour, according to Indeed, though some brands pay up to $39 per hour. Gowa hopes that trimming jobs can one day become trimming machine technician jobs, which would pay more and train workers to operate complex machinery. 

"The mantra I always followed was robots perform all dull, dirty, or dangerous jobs."

"The mantra I always followed was robots perform all dull, dirty, or dangerous jobs," Gowa said. "Cannabis to me is pretty dull and dirty, and if you use the crazy machines it has been dangerous for some people...We're not trying to replicate these machines that are already out there. But we're trying to produce a higher end product."

When it comes to better automating the cannabis industry, there's less demand for new, revolutionary products than there is for improving upon ones that already exist. Small changes, like a control system that can be preset with light and humidity adjustments for an entire 16-week grow cycle, or a single software for both planning out harvests and distributing products to better track inventory, are just as in demand as machinery. With further legalization promising expansion for the budding industry, there's plenty of room for automation to grow. 

But for now, robots will not be taking over weed.