The Georgetown House tour will be held Saturday and Sunday (May 2 and 3). Seven different houses, 14 in all, will be on view each day. Homes on tour Saturday belong to James van Sweden, Mr. and Mrs. Adrian Sanford Fisher, Mr. and Mrs. Livingston Biddle, Samuel Pardoe, Jack Wilson Lydman, Joanne Ellert an William Woodward. On tour Sunday will be the homes of Mrs. Herbert Marks, Mrs. Poe Burling, Linda Swartz, Mr. and Mrs. Mahlon Apgar IV, Mr. and Mrs. William Joseph H. Smith, Mr. and Mrs. Rodger Pauley, and Mr. and Mrs. Milton Schneiderman. St. John's Church's Chapel of the Carpenter will be open both days.

Tickets are $10 per day, available from the sponsor, St. John's Church, 3240 O St. NW. Tea and free babysitting are offered in St. John's Parish Hall. Call 338-1796.

WHEN PEOPLE talk about James van Sweden, they're usually thinking about either his garden or one of the other gardens in Washington he's designed, dug and flourished. He's done 30 at least in Georgetown, five within a block.

But van Sweden was an architect before he was a landscape architect, and his house is as interesting as his garden. This year the small row house will be on the Georgetown House Tour (see box at left).

The Victorian row house, with its handsome stone frieze, was built in 1870 as one of our speculative houses. A bow in this direction are the stained glass panels, hanging like pictures in the front windows.

The house, though small, seems much larger because of the white walls, sparse furnishings and lack of clutter. Only a few books on the spare coffee table disturb the order.

We entered through a small front hall, with a textile sculpture mounted like a grill on the glass door panel. Inside is a small living room, just big enough for seven to sit down, if one of the seven plays the harpsichord. The seven-foot-long harpsichord was built for van Sweden by William Dowd in 1960. It just fits in the niche.

The furniture is an interesting collection of modern classics. The sofa is a Charles Eames design for Herman Miller. A wooden Eames side chair, no longer made, sits on the side. "I found it by my neighbor's trash can," said van Sweden. "I offered to buy it from her, but she said it needed to be repaired and she was tired of fooling with it. So I had it fixed and upholstered. It's been a joy."

Two canvas slings on stell frames by Thonet, a classic cane Thonet chair at the harpsichord and a floor lamp complete the furnishings. An Oriental rug on the floor relieves the rust-colored wall-to-wall carpeting.

The room has several handsome paintings, including a relief sculpture by Schoenhoven, a Dutch sculptor. A set of smaller relief tiles are in the dining room.

The dining room shows the close affinity of country and modern. The sideboard and the 18th-century rush chairs are paired with a reproduction table and a handsome Shaker-style clock made by Anthony van Sweden, James' father. The two rugs are a Kelim and a Caucasian.

"This room was a dark hole," said van Sweden. "But painting it white and baring the floors helped." Ann Truitt's white painting on the wall adds to the feeling of lightness. Another wall has a large blue and red painting by Leon Berkowitz. A photograph of Martisse with a nude in his studio is the first of a 30 print edition by Brassai.

The real changes begin when you leave the dining room. Architect Pamela Heyne designed the changes with van Sweden. A small bath is tucked into the hall to the kitchen.

When we came into the kitchen, we stopped, not believing the glorious color blooming forth in the garden just beyond. One whole wall of the kitchen opens up through double glass "store" doors, topped with a deep transom. It's almost like a dollhouse where one whole wall is removed. The garden begins with a small terrace at house level. You go up a few steps into the garden proper.

The spare, cool, restrained decoration of the house is all forgotten in the exuberance of the garden. When we saw it, the tulips were in all their glory -- immense blooms, bigger than I'd ever seen before. "I treat them as them up after they're finished blooming." The garden has other glories. Ivy climbs a huge tree of heaven -- a surprise to find in a landscape architect's garden, but the effect is pleasant.

Van Sweden explained the garden is supposed to look not contrived, but natural. It does have the look of an old garden, where nature has won. Writing in the magazine Landscape Architecture, he elaborated:

"Spring brings the bulbs and the general greening. In the background a Chinese witch-hazel (Hammamelis mollis brevipetala) is covered with yellow flowers from February through March.

"In the summer two Miscanthus floridulus dominate and many ornamental grasses and herbaceous perennials reach the top height of their growth. A Magnolia virginiana in the foreground is in full leaf, permeating the air with sweet smelling white flowers. The summer garden has a feeling of tropical paradise.

"In fall and winter, the colors turn to beige and brown. Contrasting greens are provided by the ivy on the fence, the ailanthus tree, and liriope, ilex and Mahonia bealei."

White concrete rounds are dropped through the garden as stepping stones. Extensive, hidden lighting is a night bloomer.

A similar 17 1/2-by-55-foot garden, Van Sweden figures, would cost about $10,000 to $12,000 for design and execution, including retaining walls and terraces and lighting.

Van Sweden's partner is Wolfgang Oehme. The firm is listed as Oehme, Van Sweden Associates Inc. Van Sweden studied architecture and landscape architecture at the University of Michigan before going on to the University at Delft, Netherlands. He worked for several years in the Amsterdam planning office, concentrating on the World Exhibition Terrain on the Amstel River. He's a popular lecturer at the Smithsonian Associates classes, and at the George Washington University.

The kitchen itself, if you can tear yourself away from the garden, is full of white cabinets, punctuated by glazed tile between upper and lower cabinets. A well-scrubbed country kitchen table came from a University of Maryland dining hall. The cane chairs are Thonet.

Going upstairs, we noted the Persian Kelim rug hanging on the hall wall. "I like to think of it as a stained glass window," van Sweden said.

On the second floor, the large front room, larger than the living room, serves as van Sweden's bedroom and study. His father built the splendid shelves above cabinets and desk across one end. The windows are shielded by a practical and novel type of mini-Venetian blind -- the slats are wood. The big chair is the Saarinen womb chair, probably the most comfortable chair ever. The bedspread is a quilt, commissioned from Arlinka Blair. The painting is by Rebecca Davenport. The headboard has shelves and cubbyholes.

The middle bedroom, originally van Sweden's, when his office was in the front room, is now a lavish bath with a steam shower. Pamela Heyne designed the oak frieze which becomes a lighting fixture over the washbasin. Drawers under the washbasin and a wall of closets hold clothes. A Turkish Kelim is spreak on the blue tile floor.

The back bedroom, which stays full of out-of-town visitors, especially at this time of the year, has a Sheraton chest and a jewelry butler made by his father.

Van Sweden has his offices in the basement of the house. But there's no way of going from one to the other inside. "I have to walk down the front steps and down the English basement steps to work. I like my 30-second commute," he said, as he waved goodbye.