Behnke's Nurseries Co., like its best perennials, has weathered the last 70 years with panache.

Behnke's built its high-quality image and sturdy customer following by having a single-minded focus on plants. As other homegrown businesses such as Hechinger Co. succumb to stiff competition from big-box stores, Behnke's holds its own, and rings up $13 million in annual revenue by catering to diehard gardeners--the ones who order their Compact Oregon Grape Holly and Himalayan Sweetbox Sarcococca by name.

In recent years, Capital Beltway traffic has flattened sales, so the company plans to expand in the area to bring its services closer to home for most of its customers, said John Peter Thompson, chief financial officer and grandson of Behnke's founders. Thompson, like his grandparents, cares more about maintaining a good relationship with customers than expanding at all cost, but "we feel that we cannot cater to all of our customers at this site," he said.

To celebrate its 70th birthday, Behnke's will have events throughout next year at each of its three stores in Beltsville, Largo and Potomac. The company plans a rose festival and other educational and historical seminars highlighting pansies, African violets and roses, which were especially dear to the company's founders.

"I wouldn't plant any other tomatoes from anywhere else," said Lawrence Harris, a rector at St. Barnabas Church in Largo who has been a Behnke's devotee since he moved to Prince George's County in 1966. Behnke's donates plants for church fund-raisers and comes out to the 55-acre grounds to help them design memorial gardens, he said.

"Their image [in the community] is that they have very good quality plants and unusual varieties," Harris said.

Behnke's passion for plants is the legacy of Albert "Mister" Behnke, the forthright, confident German immigrant who founded the farm with his wife, Rose, in Beltsville in 1930. Albert Behnke, who died in 1992, apprenticed under his father, who was a Kaiser-appointed "meistergartner" in Germany. Albert Behnke was charismatic and encyclopedic in his knowledge of plants, according to Behnke's staff.

The late Rose Behnke was an intellectual type who, though quiet and good-natured, spoke with authority. She grew up on her father's hops farm in Germany and was famous for painstakingly cross-breeding African violets fit for first ladies, which she delivered to the White House door steps--starting with Eleanor Roosevelt until Nancy Reagan (who halted the tradition because she doesn't like violets, Behnke's staff members remembered).

Word of Behnke's professionalism spread through the area, drawing in customers from Virginia to Pennsylvania, and eventually the farm grew from eight acres to a 98-acre, $13 million-a-year operation. Now, during the peak spring months, five off-duty police officers have to direct traffic off Route 1 into their flagship store in Beltsville, and Behnke's rings up 7,000 cash register transactions a day, Thompson said.

Joel Albizo, spokesman for the American Nursery & Landscape Association in Washington, said Behnke's is a typical independent gardening retailer because it is family-owned and multi-generational, and it has strong name recognition. Before Home Depot, Lowe's and other large home improvement centers, gardening retailers enjoyed greater business.

But "what companies like Behnke's have done is played on their strengths, like their connection with the community, longevity and their seriousness of purpose," Albizo said. They have emphasized developing a personal relationship with their customers, he said.

What drives customers to Behnke's is the expertise, Albizo said. Behnke's has 150 full-time staff members at its three Maryland locations, more than a dozen of whom are degreed horticulturists, and the rest of whom receive extensive on-site training. Every plant sold on the premises comes with cards written by the staff that describe how the plant should be taken care of, what temperature and sunlight level they like and what kind of soil they take to.

But Behnke's history hasn't always been rosy. In its first year of operation, a hard winter froze all of the plants, so Rose Behnke had to pawn her wedding ring to dig them out of bankruptcy, Thompson said.

The postwar years were boom years for Behnke's, whose sales in the 1940s and 1950s accelerated mostly because of the mail-order business Rose Behnke spearheaded, Thompson said. Then, the Behnke's employed about 10 people and in the 1960s formed a partnership with two employees, Ira DeGourse and Leo Bicknese, in anticipation of Albert Behnke's semi-retirement in 1964, he said. In 1978, after three decades of prosperity, Behnke's bought an 80-acre plot in Largo, where the company grows half of the 10,000 varieties of plants the nursery sells.

Alfred Millard, chief operating officer and a 37-year veteran at Behnke's, "has been here since dirt was invented," a co-worker said. His first job at Behnke's at age 13 was packing soil into potted poinsettias. Millard, who grew up in Adelphi, stayed with the company because he liked the way the people there really cared about their plants.

Sonja Behnke Festerling, Thompson's mother, took over as president in 1995 from her brother, Roland. Festerling, who was on vacation and could not be reached, had wanted to be an actress, and runs the business with dramatic flair and forcefulness, said Thompson, 45. Behnke's is 60 percent owned by 12 family members and 40 percent owned by employees.

Thompson's business plan is as steady as his grandparents' original approach. Growth on the scale of Home Depot or other home improvement giants is not for him. In the past, larger plant retailers expressed interest in acquiring Behnke's, but that was never a serious consideration, Thompson said. "A family business is learned by osmosis," he said, and you can't write standard operating procedure manuals for experience that is learned over decades of caring about the business, he said.

"I don't want to be super rich; I just want to continue the nursery."