POT HOUSES ARE RAIDED.
Garda Commissioner Martin Callinan said criminals are attracted to the business because they can make a "quick buck".
He added: "Grow houses are a concern. We have seen it in recent times. We have some 60 detections so far.
"About 30 of those are full production line seizures. We have about 40 people before the courts.
"An estimated street value in or about EUR6million in terms of the retail value of that product."
Commissioner Callinan said these detections have been made since July last year.
He told delegates: "There could be a variety of reasons for the increase. Head shops have largely been shut down and it's low maintenance and high return."