MORE than £1m of cannabis plants were destroyed as police shut down a cannabis factory every two-and-a-half weeks in a year.

Officers raided 20 make-shift ‘factories’ in all corners of the county between April 2009 and April 2010, with nearly half the farms in Oxford, including Headington, Botley and Grandpont and put the total haul at more than £1m.

The largest factory was found in Long Hanborough, near Witney, in April last year, where 445 plants were seized.

A cannabis factory is a property which has been specially adapted to grow cannabis plants, and includes a system of fans, heaters, lights and irrigation.

On Thursday, police forced their way into a house in Webb’s Close, Wolvercote, and seized about 30 cannabis plants from pots in the garden, and in two bedrooms.

A 38-year-old man and a 59-year-old woman were arrested on suspicion of cultivating cannabis and were being questioned by police.

Last night, Ch Insp Cecilia Agger said police were always on the look-out for cannabis factories and had become more clued up to the signs over the years.

She urged landlords renting out properties to keep a watchful eye over their homes and report any suspicious activity.

She said: “If they are worried about a house in their streets, or have next door neighbours that they never see, anything strange, then it’s really helpful if they report that to us and we can look at developing that intelligence and then do a warrant.

“The worst case scenario is we will have to replace the door.”

Since 2006, police have found 70 cannabis factories in Oxfordshire, between April 2008 and 2009, 13 were uncovered. And since April officers have already shut down another six.

Chf Insp Agger said the figures showed the situation was ‘stable’.

She said it was often difficult to bring those responsible for cannabis factories to justice.

She said: “Often when you get into a cannabis factory, it can be unattended. Invariably, (the people looking after the properties) are at the bottom of the chain, they are told to look after the plants and they are not the people who have organised it.

“When it’s an attended house, if we don’t get them remanded (after being charged), invariably they disappear.”

Ch Insp Agger was reluctant to point to a particular nationality responsible for cannabis factories.

But she added: “We do see large numbers of people with Vietnamese backgrounds and that is common across the country, but I am by no means saying it is only Vietnamese people.

“We find cannabis factories in all areas of the city, but it tends to be more where rental properties are.”

There might be strange smells coming from the house, possibly deodoriser or air freshener to eliminate the smell of drug production.

  • Telltale signs include: The house may receive visitors at odd times of the day or night.

You could receive irregularities with your electricity bill.

Lights will generally be left on all day and night.

Curtains or blinds drawn are also clues.

The house might have high humidity levels and there may be lots of fertiliser or soil being delivered.