GREENVILLE, N.C. — DUST-CAKED and sunburnt, Leonard Hudson and Malcom Carmichael slump in the front seats of their Jeep Cherokee, trading gulps from a water bottle. ''This has not been a good day,'' Mr. Hudson says. ''We've been out here since daybreak, and we haven't found any marijuana.''
Every year, Lieutenant Hudson and Sergeant Carmichael, members of the Pitt County Sheriff Department's drug unit here, spend three weeks winging through the North Carolina countryside on Yamaha four-wheelers, searching for Cannabis.
Guided by airborne spotters from the State Bureau of Investigation, they usually discover about 2,500 plants: a stash worth about $5 million. This year, however, they'll be lucky to find 500.
While the sudden dearth of outdoor planting is a testament to their aggressive policework, Hudson and Carmichael say it's a Pyrrhic victory. Here and across the country, marijuana supplies are still plentiful; pot farmers have just moved indoors.
Armed with high-pressure sodium lights, tube-based fertilization systems, and hydroponic gardening kits, indoor growers have learned how to produce as many as four crops of highly potent marijuana a year in basements, attics, and walk-in closets. When it's grown indoors, police say, marijuana is nearly impossible to detect.
''The frustrating thing is that there are people in this county who we know are growing marijuana,'' Hudson says, ''but there's nothing we can do about it.''
In 1994, the Drug Enforcement Agency (DEA) destroyed 508 million marijuana plants. Of this total, however, only a tiny fraction (.04 percent) was seized indoors. Yet some experts estimate that indoor growers supply as much as 20 percent of the multibillion US marijuana market.
As their production rises, indoor growers have become far more sophisticated, using horticultural techniques like cloning and cross-breeding to maximize yield. In addition, they have shared their expertise in how-to books, counterculture magazines, and Internet sites. Each Thanksgiving, indoor growers meet in Amsterdam to trade tips at the annual ''Cannabis Cup'' - a convention sponsored by the pro-marijuana magazine ''High Times.''
According to those who advocate legalizing marijuana, like Allen St. Pierre of the National Organization for the Reform of Marijuana Laws (NORML), the rise of indoor cultivation is a direct result of the federal government's 14-year war on drugs.
The eradication effort launched by the Reagan administration in 1981, he says, acted as a ''spur to innovation'' that drove outdoor growers inside. Ironically, Mr. St. Pierre says, the war on drugs turned out to be an economic boon for domestic growers, protecting them from foreign competition, boosting prices, and hastening the introduction of more-potent pot.
Yet government eradication efforts also have raised the stakes dramatically for growers. Under a ''zero tolerance'' policy, federal lawmakers have strengthened civil forfeiture laws to the point where anyone caught growing or selling marijuana can lose all of his or her property and assets. This controversial policy helped the DEA seize $57 million from marijuana growers in 1994 alone.
In addition, a slew of state and federal mandatory-minimum sentences for drug offenders has put thousands of growers and dealers in prison. Under federal law, if a grower is caught with one plant, the grower can get up to two years in prison; one-hundred plants brings an automatic five-year sentence; and 1,000 plants brings 10 years behind bars. In Oklahoma, cultivating any amount of marijuana can lead to life in prison.
Although the vast majority of arrests result from tips from informants, police say they are getting better at finding and busting indoor growers. Infrared cameras mounted on helicopters can be used to locate ''hothouses'' or areas where growing lamps might be employed.
When such a place is located, agents check for high electric bills and taped or blackened windows, and sift through garbage.
In 1989, the Bush administration launched an ambitious operation called ''Green Merchant'' aimed at indoor growers. The DEA seized the sales records of companies that make high-pressure sodium lights - the type growers prefer. Following up on this list, agents made hundreds of arrests nationwide.
While the total number of marijuana plants DEA agents seized rose by 20 percent last year, some in Congress have questioned whether the interdiction effort is worth its estimated $2 billion price tag.
Marijuana advocates complain that penalties for marijuana farming are stiffer than many violent crimes, and that law enforcement pays more attention to pot growers than to the purveyors of drugs such as crack and heroin, because those dealers tend to be far more likely to resist arrest violently.
Efforts to root out growers and seize property, they say, promote graft within police departments and trod on constitutional privacy guarantees.
''When you shut your door, you should be free from government,'' St. Pierre says.
DEA officials counter that marijuana dealers are almost as heavily armed as other drug peddlers.
In 1994, the DEA seized almost 6,000 firearms from busted growers. In addition, they say, more stringent federal drug laws are necessary as drugs such as marijuana become more and more socially acceptable, especially among teenagers.
'War on Drugs' Sends Marijuana Growers Indoors
'There are people ... we know are growing marijuana, but there's nothing we can do about it.'
- Lt. Leonard Hudson