Medical Marijuana: Safe Use Begins With The Grower

A recent article in the Globe and Mail highlights problem that growers of medical marijuana—and, in fact, all gardeners— must address and manage: safe pest control. 

In the article, a grower is alleged to have applied some chemicals not allowed for medical marijuana to their plants. Users of the marijuana complained about health issues related to these chemicals and a recall and a Health Canada investigation ensued. 

Medical marijuana growers are entering into territory in which some of them have little experience. Good crop management requires pre-planning, expertise, and hard work. Managing a crop to prevent, reduce, and eliminate pest problems starts with the fundamentals; if these fundamentals are managed, then pesticides and fungicides can often be avoided altogether.

For instance, the 2 problems that this medical marijuana company likely faced were a fungus or mildew problem and spider mites.


When temperature, water, plant nutrition, growing media and monitoring are properly used and systems followed, the problems become much smaller and more easily solved. For instance: mildew can be prevented with good sanitation, proper watering, and soil temperature management.

Spider mites can likewise be prevented and managed with proper temperature, humidity, and watering. Regular inspections can also catch the problem when it is small, and it can be dealt with non-chemically in a number of different ways.

Unfortunately, it appears that the marijuana growers’ pay structure was significantly tied to the production levels from their marijuana plants.

When the previously mentioned plant problems occurred, rather than catch them early, prevent them in the first place, or destroy the infected crop, it is alleged that the growers used anything at their disposal to salvage the crop. This allegedly included using banned chemicals that no greenhouse with an experienced, certified, pest management team would ever dream of using. 

Medical marijuana growers need to model themselves after the greenhouse vegetable industry. These greenhouses have been growing edible crops for many years and know what it takes to grow safely, using preventative practices.

Even if these preventative practices don’t work, there are many non-chemical or gentle controls such as garlic sprays, beneficial nematodes, predatory insects, and soaps that can be used to control many pest problems. 

Experienced greenhouse vegetable growers will be in high demand if the marijuana industry grows as rapidly as the pundits. Preventative steps and the safe and correct use of pest controls is what they practice every day.