In a major reversal, Illinois regulators have proposed letting cannabis companies grow cannabis outdoors, a move that would significantly lower energy consumption and cultivation costs — though home growers would be out of luck.

State law requires cannabis to be grown in an “enclosed, locked” facility. Previously, the state Department of Agriculture interpreted that to mean that outdoor growing was prohibited, citing concerns over security and agricultural pesticides drifting into marijuana crops.

But the agency gave in and proposed the change after at least two cannabis companies won court approval for outside grows and a third filed suit to do the same. Outdoor cultivation is common in other states that have legalized cannabis, from California to Michigan. Researchers say it could save up to 76% of the energy used on indoor cultivation, helping the state towards its goal of reducing net carbon emissions. It could also lower prices for consumers.

The founder of the Illinois Independent Craft Growers Association, Scott Redman, said the move would be a “game changer” for small growers. Due to high start-up costs and difficulty getting financing, only 31 of 85 licensed craft growers have been cleared to open for business.

“For those operating, it allows a faster and more economical route to expanding to the full (state limit of) 14,000-square-foot canopy,” he told the Tribune. “For the projects still in design, it can mean that one need not spend millions on lighting and HVAC (heating, ventilation and cooling) if it is outside the budget … This is a significant step forward for the industry as far as I am concerned.”

The proposed rule change would allow licensed cannabis companies and craft growers to cultivate outside next to their existing facilities under certain conditions. The growing area must be fully enclosed by a continuous chain-link fence at least 8 feet high and topped with razor wire or other security wire; and screened or covered so that it’s out of public view from nearby streets or roads.

The outdoor grown cannabis would only be allowed for extraction, which creates concentrates for use in edible, vapes and oils. So, Redman said, it would not result in more flower for smoking, but should help small-business infusers to get more distillate.

The contentious issue was brought to a head last year when Curaleaf Holdings, the largest cannabis company in the United States, filed suit through its subsidiary, Compass Ventures, Inc. The company proposed growing in plastic-covered hoop houses next to its existing clear-roofed cultivation warehouse in downstate Litchfield. Regulators required an enclosed facility of solid walls and ceilings.

A Curaleaf spokesperson said in a statement that company officials were still reviewing the proposed change.

“While the proposed rules seem to create a pathway for licensed operators to grow cannabis outdoors for additional biomass, our position has consistently been that cultivation for any purpose that passes regulatory muster in enclosed, ambient environment structures is already permitted under the existing rules and statute …

“We remain committed to advocating for a regulatory framework that allows licensed operators to grow cannabis safely, securely and efficiently as the law currently allows.”

As for the new outdoor grow changes released Friday, they are subject to a 45-day public comment period before they could become final. The Department of Agriculture said that officials proposed the rule “to set clear, consistent health and safety standards.”

“The Department remains committed to its ongoing mission of ensuring the development of a cannabis industry that is safe, equitable and well-regulated, and is consistently reviewing its policies and regulations for areas of improvement as the cannabis industry matures,” agency officials said in a statement.

The battle over growing cannabis under the sun is somewhat ironic because hemp, which is the cannabis plant with only trace amounts of the delta-9 THC that gets users high, can be legally grown nationwide in farm fields. But intoxicating hemp derivatives generally are due to be banned by federal and state law in November.

In Illinois, the state initially allowed then tried to rescind growing in outdoor screen houses for two cannabis companies — Green Thumb Industries (GTI) Rock Island and Nature’s Grace and Wellness. Both went to court and won rulings that allow them to keep growing in screened houses, which are fenced areas with screens on top.

The rest of the cannabis industry in Illinois grows indoors, generally depending on energy-devouring lights with carefully controlled temperatures and humidity. One study estimated that the industry nationwide produces greenhouse gas emissions roughly equal to 10 million cars, or as much as all other crops combined, and greater than that of cryptocurrency mining.

Because cannabis requires about three months to grow, the Illinois climate only allows for one or two outdoor harvests a year, but that can be extended with greenhouses or other coverings.

The Cannabis Business Association of Illinois, which represents most of the largest growers and dispensaries in the state, gave a measured response to the proposed change, saying it would survey members and comment to regulators based on that feedback.

Some growers who have invested millions of dollars into indoor growing facilities worry they could be undercut by cheaper outdoor production.

“We expect this to be a significant and closely watched rulemaking, with a range of views among our members,” Executive Director Tiffany Chappell Ingram wrote in an email to the Tribune. “Outdoor cultivation raises real questions around security, cost and potential pricing and supply impacts that will affect current and future operators differently depending on their size, location and business model. CBAI’s role is to make sure all those perspectives are heard.”

As for growing at home, Illinois law limits the practice to registered medical cannabis patients, who may grow up to five plants — but only indoors.

Cole Preston, host of TheColeMemo.com website and podcast, who first reported on the outdoor grows, has called for home growers to be allowed to grow outside as well, but there is no such provision in the proposed changes.

Corporate and home licensed growers may grow in greenhouses, but Preston is hoping regulators would expand that to include outdoor growing at home.

“It’s really unfortunate,” Preston said. “It’s really hard to have an indoor growing operation. The lighting, the fans — it’s elaborate if you want to do it right. It doesn’t have to be if you grow outdoors. It grows naturally here.”

One cannabis activist said home growing is important for helping medical patients have easy access to the plant.

Madeline Scanlon, co-founder of High Focus Media, which hosts cannabis consumption events, also helped start the Illinois Cannabis Consumption Association, and an outdoor home-growing club.

Growing outside, she said, and keeping it fenced, locked and out of public view, is much cheaper and easier than growing indoors.

“Outdoor cannabis has been happening, and the sky isn’t falling,” she said. “That’s what I tell legislators.”