Twenty-eight thousand winter-worn folk, most of them gardeners and some of them properly fanatical, trooped into the Philadelphia Civic Center today for the annual great garden show, commonly called America's best.

Tremendous moving stairways dumped the friends of spring into a veritable fairyland of perfumed hyacinths, electric blue cinerarias, soft salmon tulips (many of them painted with egg whites to keep them from falling apart, since the show runs through next Sunday) and five solid acres under a roof all stuffed with everything from flamboyant orchids to modest trailing arbutus.

Not everybody was a gardener. For them, there was Elvis Presley's jeweled suit, said to be worth $100,000; it was part of the City of Memphis exhibit.

"I'd think Memphis would want to display at the Philadelphia Flower Show that they have something besides a rock star," said one.

"You aren't going to catch me on that one," said Bonny Martin, in charge of the exhibit. "We thought of the Mississippi River as a theme, and nobody liked it. They went mad for Elvis."

Old Philadelphia may be elegant, but they also know what folks like. Since 1829, when the show started -- and in the early days there were vast exhibits of pansies and other florists' flowers, the sort grown by fanciers strictly for exhibition -- the show has been a touchstone of American taste.

This year, in response to some surly comments that past shows have dealt with England and the Orient, the theme is "American Home Towns." Hence Memphis and Elvis. But these exhibits consist of huge flower arrangements and such props as the gold-studded Austrian-crystaled Elvis suit. Gardeners tend to sail right past them with an indifferent glance or even a superior sneer as they head for Chuck Gale's foxgloves.

Chuck and his daddy Charles, who are nurserymen, have spent five years raising thousands of foxgloves for the show. Normally they would bloom in June, but heating cables in the 7,000 square feet of the Gale greenhouses raise the soil temperature above that of the air, and the foxgloves hurry along to reach perfection early in March. Their shoulder-high spikes of bloom are a glory of the Gale exhibit, which is full of delphiniums (a despair of Washington gardeners since they loathe muggy nights in summer and protest by dying utterly) and roses and dozens of other kinds of spring and summer blossoms. But for years, their foxgloves failed. They had virtually none for the show. This year they hit the jackpot.

"We finally learned how to do it," said the elder Gale.

The Philadelphia Zoo, which is virtually a botanic garden itself, always has a knockout exhibit. This year the honey bears got pregnant (they were supposed to be the stellar element), though as Jane Pepper, show chairman, said:

"I think it's false pregnancy if you ask me. I think they pretended pregnancy to avoid sitting there for a week while 140,000 people gaped at them."

Instead, some cockatoos were substituted in a wrought-iron gazebo. Usually they have ducks -- not ordinary ducks, but crimson and gold types, mandarin and wood ducks. One year the ducks took against the zoo display, although it had what seemed an ideal pond for them, and sailed off to William Judd's display of a sand-barren garden. Insiders think the zoo never quite got over that. Anyway, no ducks this year.

Another display, always keenly awaited by show regulars, was entered by landscape designer Albert Vick , again showing wild American plants. This year he showed a shack, complete with Marlon Brando-type undershirt drying on a line in front, and a tin tub with empty gin bottles.

"This is Philadelphia?" roared one old-timer in disbelief.

Yes. But it was art, don't you see, and once you got past the gin, there were ethereal treasures in bloom or early leaf.

The show has a million-dollar budget, much of which is farmed back into the next show. It can cost $20,000 to $40,000 to install one of the major exhibits, a cost the exhibitors can hardly recover, so the show management subsidizes these costs at about $8 a square foot, depending on the quality of the display.

Behind glass frames one could see miniature gardens opening off miniature rooms in one section of the show, and in another there were the largest, fattest geraniums, grown like a little tree, ever beheld, to say nothing of a huge rabbit perhaps six feet high, sitting on a chair, all made of ivy. The cactus people were there with exhibits dedicated to the proposition that the cactus is chief prince of the vegetable kingdom, a position hotly disputed by the orchid people (who had recorded thunder blasting through their mangrove swamp setting), and there were a number of small-town gardens, all in full bloom.

Show hours are 10 to 9:30 daily except next Sunday, 10 to 6, and the pseudo-pregnant honey bears don't know what they're missing.