Before work and during his lunch hour, Frank Adams used to tend his half-acre vegetable garden near the NUS building on the I-270 corridor in Rockville.

Adams, building manager at the NUS, started the garden 10 years ago when I-270 was rimmed by farmland, cattle and cornfields.

"I planted tomatoes, string beans and onions," said Adams, "and I used to give them to people."

Last year, bulldozers toppled the tomato plants to make way for another of the office buildings that are popping up in the area like mushrooms after a warm spring rain.

In the last five years, more than a dozen buildings have been built along the one-mile stretch of I-270 just south of Shady Grove Road, joining "old timers" like the NUS. Kodak and Meloy Labs buildings, which were built in the late '60s.

The prime location - a five-minute drive to county offices and easy access to Baltimore - is the major reason for development along this "golden mile," according to most builders and executives.

The mile corridor also is at the heart of the Shady Grove Road study area, recently tagged as one of the Montgomery County's major warehouse, office and research and development centers. The area, along I-270 and Shady Grove Road between Rockville and Gaithersburg, was described as "a prime target for future development activity in Montgomery County" in a report prepared for the county by the consulting firm of Praful Shah & Associates.

Land values have soared in the last 15 years, according to developer William Rickman Sr. "I paid $15,000 an acre for the first piece of land I bought in 1966," he said. "Today prices are over $100,000 an acre."

Two industrial parks now flank the highway - surrounding Piccard Drive on the east and Research Boulevard on the west. More than 3,600 people are employed in the one-mile area, and hundreds more are expected when several buildings planned for the area are completed.

Among the newest additions are the Sheraton Potomac Hotel and the Brotherhood of Railway and Airline Clerks building, both of which opened in August. The Litton Bionetics research facility opened on Piccard Drive in March, and its next door neighbor is the newly completed Ward office building.

The Boston-based Valle's steak and seafood chain opened its first Maryland restaurant on Piccard Drive last year, and the Montgomery County Health Administration and Police Administration moved into its new building on Research Boulevard in December.

The "older tenants," most of whom moved into the area in the early and mid-1970s, include Tektronix, the Bradford National Corporation, National Cash Register, E.G. & G. Washington Analytical Services, Kidde Consultants Inc., Solarex, Joseph R. Harris, RACAL and Vitro's Automation Industries Inc.

This month, General Motors plans to begin construction of a 54,000-square-foot office building on four acres next to the Shady Grove Road exist. Developer Rickman, who owns four buildings in the area, is planning two more large office buildings near Research Boulevard. The B-K Dynamics building is scheduled for construction on 61 acres on Piccard Drive in October 1979.

"There is probably more than a quarter-million square feet of development in the final planning stages for this area," according to Frederick Agostino, assistant director of the county Office of Economic Development. "You have nonresidential Montgomery County in microcosm here."

"It's the old sheep instinct - when you see an area has prestigious occupants, an air of prestige goes along with it," said Martin Seldeen, president of Seldeen Development, who in 1965 joined in a partnership that owned 175 arces of land in the area because he thought it was "ripe for development."

For the veteran workers in this area, development has brought change.

"It's a mixed blessing," said Tony Clifford, assistant to the president of the Solarex Corporation, which moved to the area in 1973. "It used to be a reasonably quiet, uncongested area, but now the ease of getting to work is getting worse and worse."

Others have complaints about the development boom.

"It used to take me five minutes to get here from Gaithersburg in 1976," said NUS employe Pat Roberts."Now, even the back roads are plugged up, and it takes me 20 minutes."

"It's growing so fast that every time you turn around there's another building going up," said Geri Murphy, district services manager for Tektronix. "Two years ago there were a lot of complaints that an hour wasn't long enough for lunch because there weren't enough restaurants, but now there are more restaurants trying to meet the needs."

Despite the growth, there are still a few cornfields and enough open space to satisfy many employes.

"It's just a beautiful area," said RACAL personnel assistant Minnie Silver. "There are trees and you can take a walk around the nearby fields. It was like coming out to the county in 1971, but now there are shopping areas and more than enough places to eat."

And for employers, development boosts business.

"I'm for growth," said George W. Bushby, vice president of Kidde Consultants, Inc. "It enhances the value of the property, and activity is always a source of business.

Continuing growth in predicted for the I-270 corridor between Rockville and Gaithersburg, which has slightly more than 3.2-million square feet of building space, with about 11,000 workers. Included in that estimate is 10.5 percent of the space in the county office and research and development building and 20 percent of the space in its manufacturing and warehouse areas.

The study of the area calls the Shady Grove corridor a "prime target for future development" for several reasons. These include the future opening of the Rockville and the Shady Grove Metro stations.

Between 1979 and 1995, according the to consultants's report, the area could add 4.8 million and 5.9 million square feet of building space, enough to support 15,800 to 19,500 additional workers.