KEY POINTS:
LONDON - Three cannabis farms are shut down every day as British police struggle to keep pace with the boom in home-grown production of the drug.
More than 60 per cent of the marijuana smoked in Britain is cultivated in this country, compared with just 11 per cent a decade ago, with the plant grown everywhere from inner-city lofts to secluded patches of farmland.
An investigation by the charity DrugScope has discovered that growing cannabis has become big business in Britain and that Vietnamese gangs have a stranglehold on the illicit trade.
More than 1500 farms have been discovered in London alone in the last two years, three times as many as in the previous two years.
Police have tended to focus on the production of "skunk", one of the most potent forms of cannabis containing high quantities of the potentially dangerous chemical THC.
The research also belies the traditional image of cannabis users growing a handful of plants on their window-sill, with police saying they are recovering an average of 400 plants per raid.
The problem for police is that growers only need lights, fans and plant-pots to set up in business.
Baths are commonly used as "nurseries", with plants also crammed into attics, cellars, toilets and summer-houses.
Gangs are also renting places in industrial units in an effort to disguise the large amounts of electricity needed for marijuana cultivation.
Police, who often use handheld or helicopter-mounted heat-seeking devices to detect illicit crops, found one case of a cannabis farm wired up to nearby street lights.
Another tactic is to sow plants on other people's property and to return three months later to harvest it.
However, many of the gangs tend to opt for fast-growing plants rather than skunk because of the rapid profits they can produce.
DrugScope reports that between two-thirds and three-quarters of the farms raided by police - and ranging from south Wales to the North-east - were run by Vietnamese gangs.
Many growers, some of whom are as young as 15, are illegal immigrants forced by the gangs which smuggled them into the country to live in cramped conditions.
Police found them living in cupboards, tiny utility rooms and lofts to maximise space for plants.
Fifty cannabis farms were discovered in London last year following house fires caused by faulty lights or wiring.
Harry Shapiro, director of communications at DrugScope, said: "Growing cannabis commercially near the point of sale can dramatically increase profits, but this increases the risk of detection.
"There are significant implications for police resources in trying to keep up with the growers, who are becoming increasingly smart in establishing new farms and avoiding arrest."
DrugScope said the surge in cannabis growth in Britain has filled the gap left by the disillusionment of users with the quality of imported drug resin.
At the same time the amount of the drug produced in Morocco, previously a key source of the UK's supply, has almost halved following an eradication scheme.
GETTING RICH ON GETTING LOADED
High cost
* More than three million Britons are believed to use cannabis regularly, a higher proportion than elsewhere in Europe.
* It typically costs £30 ($84) to £80 per ounce of resin, £35 to £110 for herbal cannabis, rising to £160 for highest quality.
High production
* On March 3 about 200 plants worth £44,000 were seized at a house in Chatham, Kent. In the past five months 20 nearby farms have been shut down. On March 5 police found about 1000 plants, worth about £200,000, at a home in Forfar, Angus.
- INDEPENDENT
