A Port Colborne greenhouse used for growing medical marijuana – robbed at gunpoint earlier this week – is being investigated after police say it exceeded production limits by thousands of plants worth about $1.5 million.

Niagara Regional Police say the greenhouse at 462 Pinecrest Rd. has three medical marijuana licences limiting production to about 400 plants.

But police announced Thursday morning that 3,400 marijuana plants were found growing in the greenhouse when a search warrant was executed there Tuesday.

“The number of marijuana plants exceeded the amount allowed to grow by almost 3,000 plants,” the NRP said in a statement. “The fact that this location had almost 3,000 plants over the allowed amount, once processed, would yield a profit of over 1.5 million dollars.”

That’s based on police estimates valuing the cost of marijuana at $2,000 to $2,500 per pound.

“This makes locations such as this one very vulnerable to the criminal sub culture,” the NRP said. “The current robbery investigation at the Pinecrest Road location is a prime example.”

Police say no arrests have been made yet and the investigation is ongoing. They do, however, anticipate making arrests in the near future.

Police began investigating the facility after the armed robbery occurred there at about 4 a.m. Monday, when owners of the facility, which had been known as Muileboom Greenhouses, were held at gun point.

No injuries were reported.

A woman who answered the phone at Muileboom Greenhouses on Tuesday said, “we're OK, and that's all I can tell you.”

Phone calls left at the business Thursday were not returned.

In light of the greenhouse investigation as well as the robbery, Port Colborne Ward 4 Coun. Ron Bodner said he’s hoping it could mean an end to the marijuana being produced at the facility.

“I certainly would hope that something is done that this can’t go on again in that location,” he said.

“Nobody wants that in their neighbourhood. When you invite criminal activity in, you can’t stand for that. It just cannot happen.”

Ward 4 Coun. Barb Butters shared a similar sentiment in an e-mail she sent to residents and The Tribune.

“This may be what will finally shut it down,” she said.

Bodner said the greenhouse was not among the larger marijuana growing facilities licenced by Health Canada for the production of the plant, but instead was part of an earlier plan that allowed people with licences for growing their own medical marijuana plants to team up with other licence holders to grow the plants.

“We have to be careful not to confuse the new type of licences with the old type of licence. Everybody tends to lump those into one pot,” Bodner said. “Sorry for the choice of words.”

While the large scale licenced facilities are subject “to absolutely strict regulations and inspections,” he said that doesn’t apply to the type of facility running in Port Colborne.

“These guys are in the wild west,” he said.

Bodner said he’d like to determine how often criminal activity occurs in these type of marijuana growing operations.

Although the issue isn't listed on the agenda for Monday’s Port Colborne city council meeting, Bodner plans to ask city staff to develop a report on the issue. The meeting starts at 6:30 p.m. at city hall.

Five suspects were arrested and charged with numerous offences related to Monday’s robbery, but police believe an addition five people involved in the heist are still at large.

ABenner@postmedia.com