Editorial Feature

Harvesting Marijuana with Robots

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On October 17, 2018 Canada became the second country in the world after Uruguay to legalize the possession and recreational use of marijuana. As global opinions of marijuana use continue to become more positive, the trend of countries legalizing the use of this drug is also expected to rise. In fact, some of the most promising countries expected to legalize marijuana use in the near future include the United States of America, Mexico, Colombia, Portugal, Jamaica, France, Spain and the Czech Republic1. With this growing trend in mind, these countries will be faced with the task of identifying the best ways to successfully and rapidly cultivate this crop to meet expected demand.

Current Harvesting Techniques

One of the most important aspects of ensuring that governments are successful in gaining a profit following the legalization of marijuana will be via adequate harvesting techniques that provide high quality yields. Since marijuana plants require approximately three months to grow to their full maturity, growers must carefully monitor crops using magnification tools around the 7th or 8th week, to determine when harvesting of the plant can officially begin. Once the trichomes - which are the oil glands of the cannabis plant that are home to the primary cannabinoids such as tetrahydrocannabinol (THC) and cannabidiol (CBD) - exhibit a cloudy white color, growers can begin to implement a flush to remove any excess salts from the medium and the plant2. Note that if a grower does not perform a flush around this time, the final product’s flavor and quality will be negatively affected.

One of the first steps of the harvesting process involves the removal of large fan leaves from the plant, which can either occur when the plant is still wet or following the completion of drying processes. Wet trimming is not only faster than dry trimming, but it also prevents the plant from getting stuck to the flower, which is the component of the plant that will ultimately be sold as marijuana. Either way, the drying process is still an important aspect of the marijuana cultivation process. When drying, plants are hung upside-down on a series of strings or wires in an environment that sits at a temperature between the range of 65 – 75 °F and humidity within the range of 45 – 55%. The total time required for drying is approximately 6-12 days2.

A curing process then follows drying, during which the flowers continue to dry at a slow pace, thereby allowing the flavor of the final product to be enriched. Curing typically involves placing dried and manicured cannabis flowers into glass jars, which are stored in a cool and dark place to be examined every day. By properly curing the cannabis flowers, the aromatic compounds of this plant, which are otherwise referred to as terpenes, are preserved to allow flowers to be stored for long periods of time without risking any bacterial growth from occurring3.

Incorporating Robots

While the cultivation process for marijuana does not seem extremely labor intensive at first glance, the tremendous demand that exists for countries like Canada, as well as US states like California, Oregon and Washington that have already legalized the recreational use of marijuana, to produce high quality products at a rapid rate has subsequently increased the need for harvesters to assist during this process. For example, thousands of migrant workers travel to Northern California every year to work as “trimmers”, i.e. to carefully remove the leaves off of these plants4.

To improve production rates in a legalized marijuana industry, Boston’s Bloom Automation has developed a robot that utilizes both camera and computer-vision technology to distinguish between the different type of marijuana leaves to determine which should be kept and which should be cut and disposed of. In their design, the Bloom Automation robots utilize an articulated arm, which improves the dexterity of the robots, and a pair of shears (which closely resemble scissors), which are used to carefully trim any unwanted marijuana leaves.

To date, these robots are capable of trimming typically an 8 to 18-inch branch in as little as four minutes4, thereby making this technology a promising option to ultimately replace human trimmers at future marijuana cultivation sites. While conventional automated trimmers exist, these machines are often highly destructive to the plant and result in up to 30% plant destruction in the process5. Through the intricate technology provided by Bloom Automation, their robotic solutions not only reduce the chance of flower loss and damage to less than 5%, but also significantly reduce associated trimming costs by as much as 10 times, compared with traditional trimmer techniques.


  1. “10 Countries Most Likely to Legalize Marijuana Next” – Civilized.
  2. “Properly Harvesting a Cannabis Crop” – Professional Marijuana Grower
  3. “Your Guide to Drying and Curing Cannabis Buds” – Leafly
  4. “Marijuana ‘trimmigrants’ have the hardest job in the industry – and they could soon be upstaged by robots” – Business Insider
  5. “Benefits” – Bloom Automation

Disclaimer: The views expressed here are those of the author expressed in their private capacity and do not necessarily represent the views of AZoM.com Limited T/A AZoNetwork the owner and operator of this website. This disclaimer forms part of the Terms and conditions of use of this website.

Benedette Cuffari

Written by

Benedette Cuffari

After completing her Bachelor of Science in Toxicology with two minors in Spanish and Chemistry in 2016, Benedette continued her studies to complete her Master of Science in Toxicology in May of 2018. During graduate school, Benedette investigated the dermatotoxicity of mechlorethamine and bendamustine; two nitrogen mustard alkylating agents that are used in anticancer therapy.


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