Hoyt Catlin believes in late bloomers - in life as in gardening.

At 88, he's finally come into his own, running a fertilizer business that rejuvenates not only plants but people. The average age of the workers Catlin employs is 72. Catlin, you might say, oversees a shopful of late bloomers - or rather, still bloomers.

The company is named Fertl Inc., the way a firm's name sometimes plays on more than just its product. Fertl is not, as you already might have guessed, an ordinary company.

"The work is simple here," said Catlin who, according to friends and customers, is every bit as aggressive, astute and bull-headed as he was when he founded Fertl 20 years ago. Or before that, when he travelled around the country installing sound systems. Or before that, when he sold brown wrapping paper.

"This is a happy place. You can see it, can't you?"

Indeed, you can. In a time when early retirement is the trend and few can hope to stay on the job past 65, Fertl stands out as a determined example of what the elderly can do if encouraged to continue doing it. There is less absenteeism, less job turnover and more good will at Fertl than at more good will at Fertl than at most other small firms. There is even a little old-time music.

"Sometimes they sing during their coffee breaks," Catlin allowed about his employes. "Off key a little bit, not much harmonizing, but it sounds great."

Fertl's main product is a packet of small cubes made from potting soil and several other ingredients. Gardeners start their plants from the cubes in early spring, transplanting them outdoors after the last frosts.

The cubes are a combination of peat moss, vermiculite and perlite and plant nutrients - combined with water in cement-like mixers, packed in flat plastic boxes resembling ice-cube trays, then dried and shipped.

"I built the place, I built almost all the machines from the ground up," Catlin said proudly.

Catlin picked up the formula for the cubes in 1954 from an English company that has since gone out of business. At the start, Catlin sold his cubes directly to gardeners. Then large plant nurseries and mail-order seed companies began to order them. Today, Fertl's business is entirely wholesale.

In addition, Catlin also markets Kling, a chemically coated card that, when placed in a pan of water under a Christmas tree, helps keep the needles on the tree. He also sells a pill called 5F ("I call it that for no particular reason," he quipped) used to stimulate plant growth.

Six years ago, the W. Atlee Burpee Co. bought Fertl and kept Catlin on to run it. But last August, Catlin decided to buy his old company back. He said Burpee hadn't done enough to promote it.

Fertl employs only about a dozen people. It operates out of the corner of a large industrial/office building here. Catlin is reluctant to discuss sales or income figures, except to say Fertl is "profitable." One num- ber he does like to quote is their Over the past 20 years, Fertl has made more than a quarter of a billion little cubes.

But 25,000.000, cubes, by themselves, are hardly worth all the connection that some have been making over Fertl and its grand-fatherly chief. In recent months, Catlin has been written about several newspapers, he has appeared on national television and is even been approached by the Canadian government as an authority on employment of the elderly - all because of his unusual policy of hiring only elder worthes.

Catlin didn't start out with the idea of hiring "experienced" folks. He started in Fairfield with a crew of high school students who, he said, turned out to be "a complete loss." So he switched to older workers and that did the trick.

Much of Fertl's success, Catlin will tell you is owed to the factory's "quiet atmosphere" and to the "grace with which our senior men and women approach their daily tasks."

To anyone who asks for his vews on the elderly, Catlin hands a two-page typed document he has written entitled "Employment of Senior Citizens in Commerce and Industry."

The document makes a strong case for keeping older people on the job. It notes, in part, that "intelligence, skill, eagerness to be useful, mark a substantial proportion of those who have retired."

But Catlin concedes that companies that hire the elderly do have to make some special allowances. "Older people must not, cannot, be driven," he states. "They are not at all suited to working on an assembly line paced by a moving belt."

On that score, Fertl suits its employes just fine. It is a slow-paced, amiable, comfortable place to work. Employees come and so generally when they want, working four and six-hour days for the most part. They frequently switch job assignments. And the whole place closes down for two months during the summer.

"It's very pleasant here," said Eleanor Ferry, an ex-reporter who at 63 qualifies as the youngest in the shop. "There's something particularly nice about working with growing things. You don't feel any alienation. You know you're making people happy."

There are about 2.9 million people aged 65 and over still working today out of a total 22.2 million elderly in the country, according to the Bureau of Labor Statistics. Since World War II, the employment rate for the elderly has fallen significantly, particularly for men - the results of improved Social Security and pension benefits that have made retirement more financially feasible for many.

But one lesson to be gleaned from Fertl's example is that just because people are financially able to retire, retirement isn't always the best way to go. Most of Fertl's employes get hired through the Senior Personnel Placement Bureau, a nonprofit organization in Norwalk that helps older people find jobs. Laurence Hochheiner, the bureau's director, had this to say on the subject:

"Lots of times, a person looks forward to retirement but doesn't plan for it. This is particularly true of a person who has worked with his hands. The lawyer or doctor tends to keep going. But the other, he'll retire and try sitting on a porch for a while. Then he'll get bored with that and try travelling. When he gets bored with that, he'll come to us looking for work again."

As for Catlin, he expects to keep working for at least another decade. "It's very necessary for me to have the obligation to go to work," he said.

Catlin lives in nearby New Canaan with his wife of 55 years. He has two sons, but neither are interested in taking over Fertl. Nor, it appears, are any of Catlin's five grandchildren or two great grandchildren. What will happen to the little company with the grand purpose?

"I don't want the business to end," said its founder. "We'll just have to wait and see."