LOS ANGELES >> Dan Bifano is in a hurry, but it’s in his nature to be gracious, so he keeps his countenance serene even though gnarly traffic on the Pacific Coast Highway has made his visitors very late.

“I was afraid I would be late too,” he confides, glancing at his watch, “because I had to make a quick stop at Lady Gaga’s.”

The comment is offhand, meant to soothe rather than impress because Bifano works with the rich and famous every day as a master rosarian and garden designer. His only advertising is word of mouth, and his longtime clients include Oprah, Barbra Streisand, Tom Ford and other Montecito-Malibu-area people so private he can’t name them because of nondisclosure agreements.

He politely guffaws at the idea of a regular person like, say, this reporter, calling him for a consultation, but then hastily explains it’s because he really can’t take on any more clients. He’ll be 75 in July, Bifano says, and he’s trying to cut back so he and his husband can spend more time with their children and grandchildren.

Bifano says he’s even cutting back on another passion: cycling. He used to ride 100 miles a week. “But now I only do about 75,” he said. “I’m getting old.”

He says this seriously, even though he’s striding around Streisand’s 3-acre property like a leggy teenager. He’s tall and so lean his skinny jeans look more like a necessity than a fashion statement. He’s wearing a basic pocket T-shirt, remarkable only for its color (raspberry), a thin gray zip-up hoodie and a pair of colorful slip-on Vans that quietly tie the whole ensemble together. His salt-and-pepper hair is close-cropped like an athlete’s, “because it’s all falling out,” he laughed.

On this day in mid-March, he’s delivering the ingredients for his famous organic fertilizer “cocktail” to clients around Malibu and Santa Monica, which will be used to feed Streisand’s collection of more than 800 roses. He’s left a big stack of bags near the gate, and needs to make one more stop at Tom Ford’s home before he drives back to his own home in Santa Barbara that night.

In Streisand’s extraordinary garden, color and fragrance are paramount, Bifano said. While many features look natural or aged, like a stacked-stone bridge over the burbling stream, beside a large pond with a giant water wheel, there is nothing that’s random or unplanned because Streisand is precise about what she wants.

In March, however, the garden is just emerging from winter. The perfectly pruned roses are just beginning to leaf out and the plants in the vegetable garden are seedlings. There’s still much to be done, such as planting more than 500 burgundy coleus around one of the elaborate, custom-made structures on the property known as the “Barn,” so named because it resembles an old-fashioned red barn on the outside. The plants were carefully chosen by Bifano to be an almost exact match to its weathered, dark red paint because Streisand believes colors in the garden should match the exterior of the buildings, and/or be an extension of the colors inside.

Her vision is exacting, and usually nonnegotiable, and it’s Bifano’s job to make it happen. Which suits him just fine, since he leans that way himself.

When you’re aiming for perfection, even the smallest details count.

“It’s like a movie set,” Bifano said, gesturing to the elegant barn, brook, bridges and all the plants that tie them together. On that chilly March day, his goal was “to have everything perfect by her birthday” on April 24.

That’s not something Streisand demands, Bifano emphasizes later. It’s just something he puts on himself, and one of the main reasons his services are in such high demand.