The drought that's aggravating home gardeners, pool owners and golf course caretakers has been a boon to at least one group: police officers who hunt out marijuana plants.

With the shrubs and underbrush that generally conceal marijuana turning brown in the sweltering heat, especially in Maryland, carefully tended--and religiously watered--pot plants are sticking out like very sore, very green thumbs, law enforcement officials say.

Police in Maryland and Virginia regularly embark on airplane flights over private property and public parks in search of illicitly grown marijuana. Sgt. Kirk Holub, head of the Montgomery County Police Department's narcotics division, said that from above, the "emerald green" of marijuana stands out in a field turned barren from lack of rain.

"It's made it easier to identify the crops. It's just a lot harder to find cover," Holub said. This week alone, officials in Maryland have seized more than 100 marijuana plants. Arrests have nearly doubled, from 54 last year to about 100 so far this year.

So far this year, about 2,500 marijuana plants have been found in Maryland, up from 2,200--or $4 million worth--at this time last year.

In Virginia, which hasn't suffered the same rainfall deficits this summer as Maryland, officials have seized more than 7,500 plants, compared with about 10,000 seized in the same period last year, said First Sgt. J.C. Lewis, head of the Virginia State Police Marijuana Eradication Program.

The problem for marijuana farmers has to do with the stubby root structure of their chosen crop. The University of Mississippi's Mamhoud Elsohly, who researches marijuana for the National Institute on Drug Abuse, the nation's only legal provider of marijuana for research, said cannabis roots extend a scant six inches into the ground, unlike the roots of, say, cotton plants, which grow far deeper and require less water.

"In order to survive, [marijuana plants] need to be attended to. And if they're attended to, they'll be more visible," Elsohly said.

The problem has attracted the attention of the National Organization for the Reform of Marijuana Laws Foundation, a Washington-based pot-advocacy group. Marijuana growers "know if they go out and water the crops, it'll draw attention," said Allen St. Pierre, the group's executive director, who added that several pot farmers have told him that they are "definitely concerned about their outdoor crops."

Narcotics detectives, meanwhile, say the dilemma has forced some creative solutions. Some marijuana growers have moved their crops indoors. Others have resorted to growing the plants in pots put on the limbs of trees.

"They're using different tactics . . . [and] are more discreet in their growing habits," said Sgt. Harry L. McDaniel, head of the Maryland State Police Marijuana Eradication Unit.

While marijuana plants grown indoors are often far smaller than their counterparts, the yield is more potent and thus potentially more profitable, Montgomery County's Holub said.

Besides being hidden from the eyes of airborne officers, marijuana cultivated indoors can be grown under a more controlled climate, said Stephen D'Ovidio, a Montgomery narcotics detective. What's more, he said, indoor farmers generally don't have to worry about neighbors stealing their plants or animals eating them.

As for those plants toughing it out outdoors under the summer sun, police say the word on the street is that they hardly carry the punch of the crops grown just months ago. "It's not good. It's not good weed," Montgomery County narcotics detectives said an informant told them recently.

CAPTION: A Drug Enforcement Administration officer holds a marijuana plant cut down in a raid also involving state police and the National Guard on a Lothian farm.