Gazebos, grape arbors, "hashi" or Japanese bridges over imaginary streams sketched in pebbles -- Washingtonians are transforming their backyards into exciting environments for outdoor living. There is a nostalgic return to romanticism about it all, conjuring up images of Victorian ladies sipping tea in white wicker chairs under beams dripping with wisteria.

Even the old swimming hole is back, now slightly updated as a black-painted swimming pool that reflects the vegetation around it and blends into the landscaping of the yard.

New designs for our backyards reflect a growing informality in our lifestyles. Just as the formal dining room has all but disappeared in favor of a combined living/dining room or the even more informal arrangement of a combined kitchen/dining/family room, so too has the garden become the extended living room.

"The whole attitude towards gardens is changing," says Lester Collins, dean of Washington landscape architects and former chairman of Harvard University's Graduate School of Design's department of landscape architecture. "Yards, like our homes," says Collins, "are easier to maintain and have appeal the year round."

"Have you ever seen what an annual garden looks like for most of the year?" asks landscape architect James Van Sweden. "It's a sea of mud. People are spending the same money for perennial plants and getting something with visual interest the year round."

With the price of gas continuing to climb and holiday vacations for families becoming increasingly expensive, people are taking a second look at their yards with an eye towards spending more time in them. Decks, extending kitchens and living rooms into the outdoors, are springing up behind homes throughout the area as people make choices about the way they want to live outdoors. With more and more time spent at home, the yard becomes an important environment demanding the same kind of esthetic standards one applies to the inside of one's home.

"We went through a period not too long ago," recalls Lester Collins, "where everyone wanted great sheets of glass for patio doors and windows. During the day all that sunlight and the sense of spaciousness in the home was great, but at night people found themselves faced with yards and yards of fabric needed for drapes, or large panes of black glass facing nothing." The solution to the problem for many, says Collins, has been to take time and money to landscape the yard so that with soft outdoor lighting, the homeowner always has a view of something pleasing.

A heavy demand for evergreens and perennials seen by area nurseries reflects the heightened emphasis on the garden. Jerry Hill of Hill's Nursery and Camellia Gardens reports that the buyer is more sophisticated than ever before. Evergreens are ever popular, but, Hill says, people are also looking at dwarf plants -- the kind that don't require so much cutting back or pruning over the years.

The trend in landscape design is toward an impressionistic interpretation of nature -- gardens that don't look "planted" but appear to have evolved. Clumps of perennials have replaced rigid borders, and contrasts in textures and shapes are more dramatic. For example, the plantings installed by Collins for a Northwest Washington physician's poolside garden (see picture) show no sense of the hand of the designer or gardener at work. In fact, the design is a carefully conceived "three dimensional picture," as Collins calls it. "I work with shapes in an approach to gardening that date back to an early garden builder in China. I work for an occult or asymmetrical balance in my work." And in a burst of architectural egotism and humor, Collins sums up his attitude towards landscape design: "Nature's great, but we can improve on it."

The same attitude is expressed in a very different way by Japanese landscape architect Toshiyuki Maeda, who says his temporary oriental gardens use "miniaturized natural materials to express a disciplined design that is an impressionistic view of nature." Maeda, like Collins and Van Sweden, stresses the importance of a garden that is visually pleasing at every season of the year, reflecting different moods, emphasizing different textures, colors. Maeda likes to give a garden a focal point, and a favorite solution for him is a bright red Japanese bridge or "hashi" over an imaginary stream -- a bit of colorful whimsy in a garden that leans towards beiges, browns and evergreen tones.

Like the Victorians, many homeowners today are fascinated by the oriental garden, so many that Time-Life Books recently published a volume on Japanese gardens, another bit of outdoor exotica that is catching on.

Long a favorite garden highlight for Orientals, lily ponds have now become popular here, especially since the advent of easy-to-install fiberglass pools. George Thomas of Lilypons Water Gardens in Lilypons, Md., near Frederick, reports a tremendous growth of interest in backyard lily and goldfish ponds. Thomas' 50-year-old firm is one of three or four major suppliers of water lilies and garden-variety goldfish in the country. Thomas supplies the fiberglass pool (usually a black one because, says Thomas, "it looks deeper and it reflects the plantings around it better"), water lilies and other water plants, and the fish. For those who don't want to spend money for a fiberglass pond, Thomas says you can by a PVC (polyvinylchloride) pool liner, dig a hole, shape the black sheet to the dimensions of the hole and put a few rocks around the rim to make your own lily pond.

If pools and ponds aren't your thing, gazebos and grape arbors may offer you summer solace. Gazebos, once a popular Victorian garden structure, are making a comeback -- in wood, in canvas, in pre-fab aluminum-screened shelters. Often octagonal or round, these small fanciful shelters were viewing platforms, not unlike Chinese pagodas or pavilions from which one could catch a summer breeze and cast an eye on the garden below. The only twist to today's gazebos is the addition of a wet bar or a refrigerator to make a hot summer afternoons at home a little less painful.

A less elaborate and increasingly popular form of shelter is the grape arbor, another bit of Victorian romanticism that has crept back into out outdoor lives. Using treated wood supports and a simple lattice-work roof, the grape arbor, or more romantically conceived pergola, allows nature a chance to shelter you with just a little help. For those whose yards don't lend themselves to decks and pools, the arbor is a grape idea . . .