Philadelphia's floral tribute to `Hometown USA'. Next week's flower show to bloom with displays representing 50 states -- from Eastern train station to Hawaiian garden with make-believe rain

JANE Pepper leads the way to her office here at the Pennsylvania Horticultural Society Headquarters, apologizing for the noise of some ongoing construction. The 1986 Philadelphia Flower Show -- three years in the planning, and the biggest indoor event of its kind in the world -- is only a few days away, and the inevitable last-minute details requiring her attention are flooding in. As president of the society, Ms. Pepper could do without the added distractions, ``but these things come with the territory,'' she says -- as do interviews with inquiring reporters.

Meanwhile, the work to convert the cavernous five-acre Civic Auditorium into a floral wonderland representing all 50 states continues at a frenetic pace. By Friday evening the last of the trees must be in place, the final ``hill'' shaped up, and the paths hosed down so that judging can begin. The show opens to the public on Sunday.

The theme of this year's event (March 9-16) is ``Hometown USA,'' and the plan detailing the layout is displayed on a table in Ms. Pepper's office. Last year the show had a British theme, reflecting ``our gardening heritage.'' This year the approach is ``homespun,'' as they term it around here -- a collection of gardening styles and types reflecting every region from ``sea to shining sea'' and beyond to Hawaii.

Art Drysdale, a Canadian horticulturist, garden writer, and broadcaster, leads tours to the Philadelphia show on a regular basis. He describes the initial impact of the show as invariably stunning. Because escalators take visitors down one floor to the display area, ``you leave winter behind and descend, quite literally, into spring,'' he says.

This year the first display depicts a small East Coast railroad station -- though a much more attractively floral one than is standard in real life. At the far end of the hall will be a Hawaiian orchid garden where thunder rolls and rain falls, followed by an emerging sun and the sound of bird calls. It will do this every half hour -- provided the computer behaves.

Between these East Coast and Far West displays are examples of every other US garden type, including a special exhibit entitled ``Philadelphia Green.'' This represents Philadelphia's inner-city beautification program that began three decades ago. It is now the biggest in the United States and unquestionably the model for the nation, if not for much of the world. The bulk of its funding comes from the profits derived from the annual flower show.

Philadelphia Green began as a few sporadic vegetable plots on some abandoned city lots and now ranges from window boxes and curbside tubs to intimate ``sitting gardens'' and major food gardens as well.

What starts as a street of well-tended window boxes and watched-over trees becomes a block of beauty. When enough adjoining blocks accept such a commitment, the region is designated a ``Greene Towne,'' which entitles it to further funding and assistance.

The program has had its failures, but abounds with far more success stories -- of neighborhood commitment and newly found pride, of inner-city neighborhoods made livable again as urban monotony is replaced by islands of restful green and floral beauty.

The whole story, or at least as much as possible, will be told at next week's show.

If the show is spectacular on a grand scale, it is exquisite on an intimate scale. This year many small exhibits will focus on entryways, be they front doors to suburban homes or city apartments. Patio gardens will be plentiful; beautifying small spaces a constant theme.

The show, says Ms. Pepper, is filled with ideas that can be taken away and transplanted into a thousand different settings. There are ideas for every climate, every state, and every budget. ``Bring your notebooks,'' she urges visitors. Many do.