IF YOU ASK any keen gardener why they do it, the answer most often includes fond memories of a parent or grandparent's garden. Scratch most any gardener a furrow deep, and you'll find it's nostalgia that keeps us planting.

No one does nostalgia better than John and Toni Christianson, owners of Christianson's Nursery in the Skagit Valley. You can spot their display gardens at the Northwest Flower & Garden Show from across the room, mobbed by people standing three deep to drink in the sweet scene of weathered shed, roses and picket fences. For seven out of the eight years they've entered, Christianson's Nursery has won the People's Choice Award; the year they didn't win it, they were awarded the Founder's Cup.

Their gardens are the essence of cozy tradition, the kind of garden we carry around in our communal gardening memories even if we never had one like it. The lawns are strewn with English daisies, the sheds and fences are comfortably worn. The American Horticultural Society judges, who gave the Christiansons their highest honor this year, commented that the garden was the "antithesis of big-box stores and the mass production we now see too much of."

Perhaps it's the personal feel of their gardens that make us believe in the reality of them despite being constructed in the Washington State Convention Center. The scale is human, the aesthetic country casual, as utilitarian as it is charming. We can imagine ourselves as part of the scene . . . It takes an act of will not to open the garden gate and walk right in. How do they turn wood, dirt, plants and well-chosen accessories into a garden that's so very appealing to so many?

"John and I grew up with parents and grandparents who were avid gardeners, so we like old-fashioned," says Toni. Her earliest memory is of fragrant yellow primroses in her grandparents' garden on an Easter morning. She designs gardens from her heart and memory as much as from skill and knowledge of plants. It doesn't hurt that Toni and John have spent years collecting old windows, doors and vintage items, like the Schwinn delivery bike that was leaned up against the shed in this year's show garden.

What are the key elements that evoke nostalgia?

"Every building is the real thing, with salvaged windows, doors and glass. Even the hooks and doorknobs are old," says Toni. Such authenticity and attention to detail creates an atmosphere that facades never can.

Buildings are designed so you can peek inside. "John and I rob our home and borrow from the nursery gift shop for the interiors," says Toni. Old metal signs, antique nursery catalogs, tools and books add to the well-worn and loved feel of the gardens.

"Color coordination is important," says Toni, who has orchestrated pastel and all-white color schemes. She keeps the colors soothing; you won't find a pop of red or orange amid the pale pinks and yellows. A specific palette of iconic plants makes it into every Christianson display garden, including fragrant roses, wisteria, lilacs, iris, bluebells and pale daffodils like 'Thalia' and 'Poeticus.'

"People remember these plants," says Toni. She thinks we're drawn into the scene by the consistency of old-fashioned plants paired with vintage buildings.

From picnic baskets to old metal lunchboxes, there's always a suggestion of food in the gardens. A picnic blanket is sometimes spread on the lawn, or little stools pulled up to a wood stove with a thermos and sandwiches on display. And the sandwiches are always wrapped snugly in wax paper the way Toni remembers her grandmother wrapping them.

Every Christianson garden features a low, open fence, pathways and steppingstones. "We always force our own grass so we don't have that manicured look the show provides," says Toni. "Our gardens are never too perfect." The couple even tried, unsuccessfully, to force dandelions to bloom in the long grass one year . . . which may be the only thing at which they've failed.

Valerie Easton is a Seattle freelance writer and author of "The New Low-Maintenance Garden." Check out her blog at www.valeaston.com.