Top: Cannabis waste in Earth Flow composter. The unit (inset) is made from a refurbished steel vessel.

FlowR™, a cannabis grower outside of Toronto, Ontario, was looking for a solution to manage its marijuana plant waste. Canada, which legalized recreational marijuana in 2018, requires that cannabis growers destroy their plant waste by shredding it and mixing it with an inert substance like cat litter, sand, plastic waste, or sawdust until the waste is deemed “unrecognizable and irrecoverable.” Growing cannabis produces a lot of waste — according to one article, “for every one kilogram of legal cannabis consumed in Canada, nearly eight kilograms of cannabis plants and waste are composted, burned, or destroyed by Canadian pot growers.”

Flowr™ reached out to Green Mountain Technologies (GMT) about using composting to process its cannabis waste in order to comply with the Canadian regulations. GMT provided a 32-foot refurbished custom steel Earth Flow™ vessel that cut down on the unit’s cost and manufacturing time significantly. The composter includes a computer-controlled auger and a continuous flow design, enabling growers to add new material every day and harvest finished product every 7 days. The entire process from unloading to discharging the final compost takes between 14 to 21 days, says GMT. Temperatures in the composter reach 55°C, which kills pathogens. Flowr™ installed the unit, which also gives the company access to a nutrient-rich substrate for continued growing operations, saving money on purchasing inputs for cannabis production.