One of Washington's most familiar landmarks, Johnson's Flower Center on Wisconsin Avenue NW, is packing up its lush rows of hanging plants and flowers to make way for bulldozers that will soon level the building so construction can begin on a sleek five-story office/retail complex.

The center, which has leased its current site at 4020 Wisconsin Ave. for the last 12 years, is moving from a sprawling four-acre lot to a much smaller location a few blocks up the avenue at Tenley Mall.

The move, according to representatives of the flower center, will force them to reduce their stock by at least 35 percent. And the owners are threatening to discontinue the center's nursery operations in the District unless they get permission from the city's Board of Zoning Adjustment to use a vacant lot at the back of Tenley Mall to store nursery plants.

"We have 16,000 square feet now and our new location at Tenley Mall has half that space," said Ray Johnson Jr., president of Raymond T. Johnson Inc., the company that owns the flower center. His father started the business in 1933.

News of the move, expected to take place early next month, has longtime customers upset.

"I think it's awful. They're trying to squeeze all this into half the space," said Cecilia Klevan, looking over the center's spacious displays of flowers, shrubs, plants and garden decorations.

Klevan, who lives in a McLean Gardens apartment on Wisconsin Avenue, will actually be closer to the flower center once it relocates. But for her, convenience is not the issue.

"They're not going to have room for their nursery," she said. "I'm very upset about it."

The planned office complex replacing the flower center is one of many large projects developers are proposing to build along Wisconsin Avenue NW, much to the alarm of residents who own property that abuts the busy corridor.

"The project will be approximately five stories high, with office space, a restaurant, substantial underground parking" and a six-screen movie theater, according to Terry Aiken, spokesman for the Holladay Corp., which is developing the site jointly with the Donohoe Construction and Development companies.

The Holladay and Donohoe firms have a "very long-term" lease on the property with the owners, a private trust of the Anita Eckles family, Aiken said.

Despite the flower center's hopes for expanding its new quarters a bit, more than 40 neighbors who live behind Tenley Mall have signed a petition opposing the use of an adjacent landscaped lot as a nursery.

"Right now that land is sort of like a little park," said Joel Odum, who lives two houses away from the lot. He said that when Tenley Mall was built in 1976 there was an agreement between the developer and the neighbors that the land would remain as is for five years.

None of the neighbors renegotiated that agreement in 1981, Odum said, because the property had remained untouched.

Before moving to its current and soon to be vacated site, Johnson's Flower Center was located on the lot now occupied by Tenley Mall.

The new store, which will be located at the back of the mall, will have only 21 parking spaces, and members of Advisory Neighborhood Commission 3E, representing the Tenley area, say the reduced parking may pose a traffic problem.

Edward Shanbacker, ANC 3E commissioner and secretary, said neighbors are concerned that the owners of Johnson's Flower Center have not contracted to have any traffic studies done.

"The commission made it very clear that when Johnson's comes to us seeking support of the zoning variance we will ask to see a detailed traffic study," said Shanbacker, whose commission advises the Board of Zoning Adjustment on whether to approve or disapprove applications for proposed zoning variances. If an application is filed a public hearing must be held by the board. Gordon Sheridan, general manager of Johnson's, said the smaller location will not cause traffic congestion, even if the store wins permission to use the back lot for nursery storage.

He said Johnson's nursery operation is busiest in the spring and in December when Christmas trees are sold.

Sheridan said Johnson's and the Donohoe firm, which also partially owns and manages Tenley Mall, will apply jointly for the zoning variance, but he does not know when. The lot is now zoned for residential use.

Johnson has personally gone door to door since August getting more than 1,000 signatures from Tenley residents on petitions supporting the zoning variance.

Without the zoning variance, Johnson said, the nursery will be moved out to one of the center's other stores, which also operate in Rockville and Kensington. Johnson said he is looking at locations in Virginia and Capitol Hill as sites for more stores.

Half of the approximately 80 employes at the Wisconsin Avenue store will be moved to the stores in Maryland once the business moves to Tenley Mall, Johnson said.