ABC

Urban farming is usually thought of as a niche business for high-end food produce. In Chicago, it has taken on a new meaning.

Police in a helicopter stumbled upon what may be the largest outdoor pot farm in the city's history. Planted in rows and spread over an area the size of two football fields, as many as 1,500 plants averaging 6-feet tall were growing amidst heavy brush in an industrial area on the city's South Side.

"This would not be visible from the street," said Chicago Police Superintendent Garry McCarthy at a press conference today. "It's surrounded by a huge field that you wouldn't see anywhere (but) from the air. "

He estimated the hidden pot to be worth $7 million to $10 million.

The discovery was noteworthy not only for the size of the growing area but for the size of the plants themselves, some as tall as Christmas trees, according to police. "Usually you see a marijuana plant that's 3-feet high. These resemble plants that you'd see out in California, running anywhere from 4-foot to 8-foot high," said Nick Roti, head of the Chicago Police Organized Crime Bureau.

There was camping equipment on the scene thought to be used by the grower or dealer to guard the illegal farm. Officials believe the plants were within few weeks of being harvested. "The guess is these were probably planted in the spring," said McCarthy.

Police will haul out the marijuana and burn it at a disposal site used by the bomb and arson squad.

But McCarthy said the importance of this discovery is more than just finding and destroying so much pot. Busts like this put "the squeeze on the finances of organizations" whose drug profits spread violence.

"Whoever harvests this marijuana is obviously running a large-scale operation," McCarthy explained. "And at the same time the profits from that will be used to purchase firearms. And that's where the violence comes in- is the competition for the markets."