Some signs that a house might be the site of an indoor marijuana farm:
- The windows are often covered and the blinds drawn. There may be excessive condensation around the windows.
- Electrical outlets may be rigged to divert power from neighboring homes.
- The houses are largely unoccupied. People stop by periodically to mow the lawn or do other chores, then leave.
- There are guard dogs, ''Keep Out'' signs or other security.
- In winter, after a snowfall, the house may be the lone home on the block with no snow on the roof. (Heat from the lights often melts the snow.)
By THE ASSOCIATED PRESS
LAWRENCEVILLE, Ga. (AP) -- In Coldwater Creek, a middle-class housing development outside Atlanta, the neighbors mind their own business and respect each other's privacy -- ideal conditions, it turns out, for growing marijuana in the suburbs.
Police this month raided an utterly ordinary-looking red-brick house on the block and broke up a pot-growing operation with 680 plants arrayed under bright lights.
''You'd never know from the outside. I guess that's the idea,'' said Doug Augis, who lives with his pregnant wife and a toddler in Coldwater Creek. ''That doesn't give you a really good feeling.''
Around the country, investigators are increasingly seeing suburban homes in middle-class and well-to-do neighborhoods turned into indoor marijuana farms. Typically investigators find an empty home, save a mattress, a couple of chairs, some snacks in the fridge and an elaborate setup of soil-free growing trays.
Grow houses have been a problem for years in California and Canada, but investigators are now seeing scores of them in the South and New England. In the past six weeks alone, more than 70 have been uncovered in northern Georgia -- nearly 10 times last year's total for the entire state. Only one was busted in 2005.
Indoor pot farms also have been discovered in recent months in residential areas of New Hampshire, Pennsylvania, New York, North Carolina and Florida.
Crackdowns in Canada and elsewhere have apparently led some operators to move into parts of the United States where the public and police are not as familiar with the operations and less likely to detect them, authorities say.
''They can go in and basically fly under the radar,'' said Ruth Porter-Whipple, spokeswoman for the Atlanta field division of the Drug Enforcement Agency. ''These aren't neighborhoods where they would stand out.''
In Georgia, the latest busts averaged about 200 plants per house. With each plant yielding $4,000 on average per harvest, that works out to about $3.2 million per year, considering the plants can be harvested every three months.
The DEA said more than 400,000 plants with a potential annual value of $6.4 billion were seized from grow houses in the U.S. last year -- up from about 270,000 the year before. That is less than 10 percent of the marijuana plant seizures in the U.S.; most pot is grown outdoors on farms and in ditches, backyards and gardens.
Grow houses typically grow marijuana hydroponically -- that is, using a nutrient solution instead of soil. They also use 24-hour-a-day lighting to produce plants more rapidly. The marijuana is usually cut, dried and packaged on the premises.
Typically, the windows are covered up, and the electrical system is rigged to hide how much juice is being used.
Nearly all of the grow houses busted in Georgia were connected, police say. Fayetteville resident Merquiades Martinez -- a Cuban immigrant -- and his wife, a real estate agent, are accused of recruiting other Cubans to buy homes that cost $300,000 to $450,000.
Investigators employed tips, surveillance and information from the power company on electricity usage to find the Coldwater Creek grow house and other operations.
It was a string of electrical fires that led New Hampshire authorities to more than dozen grow houses in December. (Marijuana grow houses often have rows of power strips and spaghetti clusters of extension cords and other power lines.)
''They are very sophisticated, probably the highest quality of marijuana we've seen in years,'' said Lt. Terry Kinneen, commander of the New Hampshire State Police narcotics unit.
In another elaborate scheme, more than 50 houses with thousands of plants recently found in Florida were traced to marijuana financiers in New Jersey who offered ''relocation packages,'' with 100 percent financing for the homes. Buyers would agree to operate a grow house for two years, after which they could sell the house and split the profits with their backers, or keep growing pot.
The big advantage of such operations is the privacy that comes with being in a community full of people so busy working and raising their families that they don't know the neighbors well and pay little attention to what is going on next door.
When Tom Paige met a woman living three doors down last summer, she told him that she and her husband wouldn't be around much.
''As I remember, they had some kind of boat business in Florida and they were splitting time between here and there. I didn't think anything of it,'' said Paige, president of the homeowners association in Waterford Place, another Lawrenceville neighborhood where a grow house was found.
A few months later, the couple put up a for-sale sign.
''They were taking care of the house and taking care of the yard,'' said Paige, a security contractor trained to notice suspicious activity. ''As we found out later, they were taking care of other things.''