The Netherlands’ biggest licenced cannabis producer has been ordered to reduce the smell of marijuana wafting across nearby houses from its greenhouses within a week or risk shutting down.

CanAdelaar, which operates from former tomato greenhouses the size of seven football pitches in Hellevoetsluis, has been growing marijuana under licence as part of a government experiment with legal weed for two years.

The court decision follows more than 2,000 complaints from some 300 residents. The smell arises when the greenhouse windows are opened to ventilate, allowing cannabis odour to spread widely through the area.

CanAdelaar says it is already installing air filters and that the threat of fines of up to €3.5 million amounted to a “disguised closure.”  But the court called the current situation “very serious” and said the rules would remain in place.

Researcher and cannabis expert Nicole Maalsté warned the case could undermine the legal weed experiment. “There are only seven growers actually producing at the moment. CanAdelaar is very important. If it drops out, coffeeshops will have to turn back to the illegal market. Then you can say the trial has failed,” she told broadcaster NOS.

The health and justice ministries said there is still enough capacity to supply the participating coffeeshops and that a waiting list of growers is available if needed.