The City and County of Denver’s Department of Safety and Well-Being’s recent unanimous approval of an amendment to its municipal code will bring major changes to non-licensed marijuana growers.

According to a March 4 Denver Westword article, the amendment places a 36-plant maximum limit per 3,000 square feet on any non-residential, non-licensed marijuana growing zone within the city. Licensed marijuana cultivation facilities are exempt from the limit.

Because Colorado law allows all adults over 21 to grow up to six marijuana plants for recreation, many people choose to grow their six plants cooperatively in large, warehouse-like spaces. The 36-plant limit on these non-licensed warehouses was put in place to prevent health and safety hazards like overloaded electrical systems, blocked emergency exits and mold growth, among others.

The amendment, bill request 15-0109, received co-sponsorship from the Denver Fire Department. Along with forklift truck-related hazards, which are responsible for about one in four warehouse accidents, fire also poses a major safety risk, especially in a warehouse filled over its capacity with marijuana plants and electrical systems.

Currently, Colorado’s fire codes for its marijuana industry are largely based on the International Fire Code; none of the Denver Fire Code’s chapters offer any specific provisions for the industry. Fire codes vary by type of marijuana business, as well, between labs, dispensaries, grow facilities and manufacturers of infused product, FireEngineering.com reports.

The Department of Safety also drafted the amendment in an attempt to crack down on the black market and support licensed growers; currently, as much as 40% of Colorado’s cannabis supply comes from non-licensed growers.

Luke Ramirez, who owns a marijuana dispensary in Denver, said non-licensed growers are able to profit by selling their product on the black market, avoiding taxes and compliance requirements, the Westword reports.

If found to be violating the amendment’s terms, penalties up to one year in prison and a $999 fine would be given.