JIM AND DOROTHY HUSSEY have been carving a vertical garden out of the steep slope behind their Laurelhurst home for 44 years. It was a noteworthy garden years ago when Sunset magazine called it "the billy goat garden." You can't help but be reminded of the agility of mountain goats as you watch Hussey follow the steep switchback paths up the hillside, seemingly clinging to the bank as he stops to deadhead a rhododendron or pull a weed. Hussey describes it as "hanging by your teeth half the time."

Working on a 45-degree slope has its challenges. All plants, soil and building materials had to be carried up from the street below, the hillside extracting its price in sweat and toil. The garden began when seven big hemlocks were cut down and left in place to slowly rot, thus stabilizing the slope and enriching the soil. The hill has shifted a bit in the ensuing years, but some of the existing walls are the ones Hussey first put in nearly a half-century ago.

He found early on that 2-by-4 timbers weren't strong enough to support the slope; now nearly all the little walls that support steps and pathways are built of 4-by-4 or 4-by-6 treated lumber. Hussey describes how two helpers sat on one end of a plank while he went way out on the end to pound in the metal supports for the walls and steps. Hussey had to rope himself to trees for some of the early construction work.

Dorothy Hussey was a landscape architect and one of the founding members of the Northwest Horticultural Society, but the evolution of the garden most reflects the designs of her architect husband. It has been painstakingly chiseled from the hillside, its topography, more than the plantings, creating a uniquely personal garden.

When asked how he began such a daunting task, Hussey says he simply started at one end and "it just sort of grew." He hacked out paths, built walls, squeezed in steps, found space for little platforms and benches, ideal for both resting and viewing the garden. He has just finished the top path, completing the navigation system of this seemingly unnavigable hillside with a network of about 70 steps. Hussey put in one of the stairways three times before he got it just how he liked it.

Another big job over the years has been amending the clay soil. Hussey has huge compost piles going in a lower corner of the garden and he is constantly adding rich organic matter to planting holes or spreading it over the top of the soil. Early on he installed a drip watering system; it was impossible to run sprinklers on the slope and keep dirt where it belonged.

Interestingly, Hussey feels restricted in his choice of plants more by lack of sunshine than by rugged topography. With the same attitude he showed toward the imposing incline, Hussey has tried plants requiring more sunshine than he had to offer. He gave them a chance to get used to more shady conditions, he explains, and has found that many have thrived in less-than-ideal conditions. He points out a thick patch of healthy green mondo grass as an example of a plant that has adapted beautifully to its spot in the shade of a large rhododendron.

The garden is at its best early in the season, ablaze with the bloom of hundreds of rhododendrons and azaleas. The Husseys bought most of their plants from local plant sales over many years. The species rhododendrons were raised from seed brought from India.

The early pale greens and livelier chartreuses of emerging groundcovers and euphorbia soften the varying colors of the rhody bloom. Ornamental cherries, epimedium, vinca and little bulbs bloom in the spring, giving way to the green of hostas and ferns during the summer. The hillside is a tapestry of textures with its flowing masses of groundcovers punctuated by mossy tree trunks. All the trees have been pruned up high to showcase the trunks and let in as much sunlight as possible.

Familiar plants become extraordinary when you look up into clumps of downward-facing hellebores, brush past the curve of smooth tree trunks as you hug the steep cliff, or look down upon plants from the long diagonals that intersect the garden.

A garden with so many rhododendrons means a lot of work in early summer, when they all need to be deadheaded. When Hussey tells me that one summer he picked 19,000 spent flower heads, I am incredulous - at the amount, and that he kept track. He explains that he gets so bored with the task, that he keeps count up to a hundred, then puts a leaf in his pocket as a marker, tallying up when the job is completed. That year he ended up with 190 leaves in his pocket!

Such thick planting attracts a great number of birds. The trees around the deck and house are hung with bird feeders, including one "bird condo - a bed and breakfast for visiting birds," says Hussey.

A large deck on the west side of the house catches the most sunlight the garden has to offer. Here Hussey grows half-barrels and pots of tulips, followed by lilies and other sun-loving flowers. Carefully tended bonsai line the railings.

Counterpoint to the naturalistic feel of the garden (if anything so arduously created could be called natural) are the objects that seem to spill out from the Hussey's extensive collection of Pacific Northwest art. The interior of the house is a gallery of masks, baskets and carvings; outdoors, art is integrated into the landscape. Beach stones, mosaics, tiles, pedestals, special stones and driftwood make up the walls, line the steps and hang against the house. Many of the objects were salvaged during Hussey's days as an architect, with a short garden wall built of tiles from the fireplace at the old Broadmoor Country Club. These touches personalize as well as enliven the garden, calling attention to the details: the construction of the garden becoming the art of the garden.

After working the hillside for more than four decades, Hussey still looks forward to new projects. New terracing is planned, and Hussey says this is the year to work on refining and controlling the groundcovers. He is also working on a new garden at Meerkerk Rhododendron Gardens on Whidbey Island, which will be dedicated to his wife.

And what advice, born of many years of experience, does Hussey have for a new hillside gardener? "Buy a flat piece of property," he laughs.

Valerie Easton is a horticultural librarian and writes about plants and gardens for Pacific Northwest magazine. Her e-mail address is vjeaston@aol.com Gary Settle is the picture editor for the magazine.