Dutch police have raided 55 shops selling equipment to grow marijuana over the past month, confiscating mainly lamps and filters, the AD reports on Tuesday.

At least four ‘grow shop’ owners have been arrested. Legislation making it a criminal offence to help people grow marijuana came into effect on March 1. If found guilty, so-called facilitators can be jailed for up to three years and fined €81,000.

Most of the raids were in Noord-Brabant and Zeeland provinces. Noord-Brabant is reputed to be at the heart of the Dutch marijuana production industry.

Many grow shops have been transforming themselves into regular garden suppliers in an effort to get around the ban. Some, for example, state their equipment is expressly to be used to grow bell peppers.

Grow shop owners argue their products are used by small-time growers who produce cannabis for personal use. Police turn a blind eye to the possession of fewer than five plants.