Have you heard about AmeriFlora '92? It may be the best-kept travel secret of the year.

Why?

For starters, you know this is the 500th anniversary of Columbus's discovery of America. So any community named Columbus has a stake in the celebration.

AmeriFlora is just that. The promoters call it "America's celebration of discovery," but it really doesn't convey the message. Think of AmeriFlora as a vest pocket world's fair or, better still, a piece of heaven set down in an 88-acre park in downtown Columbus, Ohio. When was the last time you had a glimpse of the gates of heaven?

Indeed, AmeriFlora has something for everyone. In an effort to pique your interest in seeing AmeriFlora for yourself, I'm presenting some of highlights of what I saw there last week.

Community of Nations Gardens. This floral exhibit of about 10,000 square feet has got to be one of the main roads of heaven. The visitor is greeted by a dense ocean of pristine, white petunias against an elliptical backdrop of dark purple petunias. Here and there, purple petals danced among the white to accent a perfect floral marriage of petunias. There were other luxurious petunia gardens to be seen, but none that rivaled this one. Guaranteed, you'll want to recreate this display in your own sun-filled garden next spring.

Woven in adjoining displays are exemplary gardens from Africa, Australia, Canada, Germany, Britain, Holland, India, Japan, Korea, Malaysia, Monaco and Russia. Fresh orchids are flown in daily for the Malaysia exhibit.

Franklin Park Conservatory. This imposing edifice was built almost a century ago and expanded specifically for this floral exhibition. You are swept through climatological areas hosting plants of different regions. There is the tropical rain forest dotted with epiphyllums growing in crotches of huge scheffleras and palms; ferns thrust their foliage out in all directions.

You descend a granite path below a rushing waterfall as you enter the mountain environment of azaleas, camellias and rhododendrons. You discover many of your favorite indoor plants in yet another transition zone, capped with searing temperatures in the desert garden.

Finally, you work your way through magnificent water gardens and a tropical cloud forest.

Old World Rose Garden. You've seen roses before, but not 150 varieties in a half-acre setting. The names are a who's who of roses: Peace, Chrysler Imperial, Helen Traubel, John F. Kennedy, Cary Grant, Eclipse, Mr. Lincoln, Queen Elizabeth, Garden Party, Brandy, Double Delight and Tiffany. If you love roses, you'll want to check the plants for signs of problems. In our tour last week, we couldn't find any signs of black spot or powdery mildew. Oh yes, some tea roses created by Ben Williams, Washington rose hybridizer, were on display.

Smithsonian's Seeds of Change. If you've toured the National Museum of Natural History recently, you have a good idea of what this Smithsonian exhibit is all about. A must for everyone, including children, this exhibit focuses on the exchange of plants, animals and peoples. The "five seeds" stemming from this interchange were corn, potatoes, diseases, horses and sugar.

Your visit ends with a mind-boggling multimedia show that connects distant continents and multiple civilizations. You'll encounter a 15-minute wait in the afternoon because lines are long, but no wait if you make it your first stop on arriving at the park.

O.M. Scott World of Grasses. We've never seen so many different grasses displayed at one time, but here it was: Penncross bentgrass, tall fescue, Kentucky bluegrass, fine fescue, perennial rye, zoysia, buffalograss, centipedegrass, St. Augustine, bahiagrass and Bermudagrass. On the sloping hill is a gargantuan map of the universe, with appropriate grasses growing in each of the continental borders.

America's Backyard Gardens. You'll feel at home here because this is where most of us spend our leisure hours. There are demonstration gardens for low maintenance, recycling, container gardening, gardens for wildlife, raised vegetable gardens and a display of the All American Selections for '92, including dianthus, geranium, pansy, salvia, verbena and vinca.

As you stroll the paths, breathtaking displays of plant materials greet you at every corner. You'll want to bring many rolls of color film to photograph as many floral arrangements as possible, including markers identifying plant varieties. There are knot gardens to be seen, assorted geometric displays that are dictated by the lay of the land and adjoining exhibits, and many water gardens that you can duplicate at home.

For the child in all of us, there are a host of surprises awaiting visitors. Media presentations include a number of specially produced films: "I Love This Land" depicts the universe as seen through the eyes of young children; "Seeds of Genius" is a video-wall experience that depicts the determination of Thomas Edison, an Ohio native whose inventions are legendary; and the General Motors Corp. film "World Song," takes a journey across nations and continents that ties peoples and races together.

Walt Disney celebrates 20 years of theme parks with an animal topiary garden moved from Orlando, Fla. There are wild animal shows throughout the day for youngsters, including some on the endangered species list. Mimes and cartoon characters amuse tourists during the day, and entertainers take the spotlight day and night at the International Amphitheater. B.J. Thomas was in the spotlight the day I was there.

AmeriFlora is for everyone, children and adults alike. Last week, the pace was easy and comfortable. Weekday attendance usually runs from 15,000 to 20,000 visitors, higher on weekends, but we saw no major lines except at the Smithsonian exhibit. We liken the crowd to the ones you would encounter visiting any of the Washington museums on summer weekdays.

If children accompany you, they won't want to leave at closing time. The favorite is a Victorian carousel that's been moved to Ohio after previous stays in California, Oregon and Texas. Children ride as many times as they want, so expect tears when it's time to move on. If youngsters love to dig (and they do), they're welcomed at a digging site that provides appropriate tools. When they're good and dirty, clean-up facilities will make youngsters as good as new.

Senior citizens get priority attention, too. Trams move from one area of the park to another. Handicapped facilities are everywhere, including ramps for wheelchairs at every exhibit. Wheelchairs are available for rent at the main gate.

As for food, it's when and where you want it. There are sit-down lunch and dinner facilities throughout the park. You can sample international cuisine in the Taste of Nations Pavilion where Asian, Belgian, Greek, Italian and Mexican foods are prepared. The International Cafe features light fare, but there are fast-food centers everywhere; carts selling soft drinks, popcorn and pretzels were always at the next exhibit area. In late afternoon, we quaffed down an imported beer in the German food hall while the oom-pah-pah band entertained the crowd.

And was AmeriFlora clean. We saw no napkins or spilled food on the paths, much less in exhibit halls. If people were this clean outside the park, we could save megabucks on sanitation.

Now, if you'd like to reconsider your summer travel plans and trek west to Columbus, call the Greater Columbus Convention and Visitors Bureau toll-free at 1-800-234-2657. Packets of information will help you make travel plans and hotel accommodations. AmeriFlora runs until Oct. 12, Columbus Day, but the sooner you discover this bit of heaven, the better next year's garden will be.

Jack Eden is the host of "Over the Garden Fence" Sundays from 10 a.m. to 1 p.m. on WTOP Radio (1500 AM). "The Garden of Eden" television program airs live at 8 p.m. Mondays on Channel 21 of the Montgomery County Cable System, and weekdays on other cable systems in the Washington area.