It was the largest illegal marijuana grow operation ever shut down by Niagara Regional Police.
Police have been investigating the grow-op at Third Street Louth and Main Street in St. Catharines since May.
Police searched the place on Tuesday and have arrested 11 people.
They face a list of drug related charges.
More than 17,000 plants were seized by police.
The value is about $34-million.
2 Niagara men arrested by Toronto Police
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Niagara Parks Tree Planting Day - Sat. Oct. 24
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