FLOWER FOOD. How Bob Peters made it big with his popular fertilizer. GARDENING

IT was in the waning months of World War II, and Bob Peters was bored. The technical sergeant from Pennsylvania had spent much of the war entertaining his fellow GIs in Italy with some talented strumming on a guitar. Once he had even accompanied the glamorous Marlene Dietrich when she appeared in Naples. But now Sergeant Peters was recuperating in a military hospital. He suddenly found himself with little to interest him ... until he stumbled across a ``very special'' book in the hospital library. It listed 20,000 careers in alphabetical order.

At the time Peters had little idea what profession to pursue once the war was over, so he began with the letter `A.' When he reached `F,' he stopped.

Nothing had captured his imagination until he came across the term ``floraculture.'' Its effect on him was instantaneous and surprising, because as a youngster he had done no gardening beyond helping his mother plant some of her spring-flowering bulbs.

Even so, he felt instinctively that he had found the career he would follow.

If there were a more appropriate one farther on in the book, Peters would never know. In any event he's had reason to be very satisfied with the direction floraculture has taken him in the intervening years.

Peters' Professional Plant Food company, which he founded in 1952, has led the way in dry soluble fertilizer development for the greenhouse industry in the United States. Currently it supplies more product to the greenhouse trade than all others combined. Exports, long a significant earner for the company, have increased in recent years with the decline of the dollar.

But what is an established success story today had some rather wobbly beginnings in the early post war years.

After graduating from the Long Island Institute of Agriculture in Farmingdale, N.Y., where plant nutrition was his major interest, Peters set up a soil testing service.

This was the way of the future, he could see, and his newly aquired skills would surely prove invaluable. It was a flawed assumption. A $3,000 investment in direct mailing to 16,000 commercial growers brought back exactly two inquiries!

So Peters took his message on the road in a surplus Army jeep bought with $350 of borrowed money. He would be an on-site consultant, but the first grower's response was a blunt: ``We don't need that.'' The next five said very much the same thing.

At the end of the year he had earned exactly $258 for his services. If it hadn't been for understanding parents-in-law, with whom he and his wife stayed, he would have been out of business almost as fast as he went in.

Then something fortunate happened.

Growers, particularly carnation producers, who were plentiful at the time, suddenly adopted soil sterilization, using steam. This saved them the effort of changing bench soils in the greenhouses every year. But it also threw soil fertility way out of whack. Suddenly Peters's skills were in demand, and the days of $2-a-night motel stops were soon a thing of the past.

Spurred on by the fact that the most suitable fertilizer formulations for his various clients were seldom available, Peters began manufacturing - or rather blending - the various ingredients himself.

For the next eight years he was lab technician, blender, salesman, consultant, chief executive officer, and janitor all rolled in one. But he found the work to his liking and the company grew.

Again it was the carnation that helped Peters get established. His 20-5-30 (nitrogen, phospherous, potassium ratio) blend suited the needs of the once dominant flower to a tee. For this reason, Peters finds it regretful that carnation production has all but vanished from US shores.

The jet age, with its economy and speed of delivery, did in cut-flower production in North America he says, noting that most carnations now come from Central and South America, where lower wages and a more benign climate make for a cheaper end product.

Over the years Peters has developed a range of formulations for professional growers and the consumer that is not matched elsewhere in the industry. This is one reason why exports are increasing.

Bags of fertilizer - stacked in rows 10 feet high on the morning I visited his plant - were nearly all destined for growers in Holland.

Shrewd people the Dutch, says Peters with a grin. They import a low-cost item from the US, and a couple of months later export it back as high quality cut flowers.

IN the laboratory just in back of his office, Bob Peters pours room-temperature water into a clear glass beaker and adds the appropriate teaspoonful of fertilizer. A few stirs with a glass rod, and the water turns blue. Within three seconds the fertilizer is fully dissolved.

It must dissolve ``faster than sugar in hot coffee,'' or it doesn't meet the Peters standard.

Then comes the prime test for all water-soluble fertilizers: I place my hand behind the beaker and look through the blue-colored solution. The outline of my fingers is clearly visible. An hour later the clarity is still the same, and there is no accumulation of undissolved sediment at the bottom.

Any sediment that settles out after a ``soluble'' fertilizer has been standing for some while indicates ingredients ``that would not be available to the plant,'' Peters points out. To get such high solubility, fertilizers must be made of highly refined ``technical grade'' materials.

What results is a product with minimal impurities.

After decades in which farmlands and backyards alike have been overchemicalized, in the view of many, the question of purity with any soil treatment is taking on increasing importance.

Organic gardeners and farmers have long avoided anything but natural fertilizers with the contention that chemical fertilizers damage soil life.

But there is a small school of thought among them that questions this concept. Chemical fertilizers alone are not the problem, these adherents say, but rather the impurities, particularly chlorine, that inevitably accompany the cheaper, dry chemical fertilizers.

Philip Wheeler, of TransNational Agronomy Ltd. in Grand Rapids, Mich., is one who thinks this way. While he promotes natural farming methods and soil building, he also sees a place for ``chemicals of high purity.''

Mr. Wheeler's own tests show soil life as well as plants benefiting from judicious applications of high quality, water-soluble chemical fertilizers.

Numbers of beneficial bacteria, feeding on the freely available nutrients, jump dramatically within a day or two of the application, he says. As these bacteria die, they release the nutrients to the plants. In effect, the bacteria have taken a highly soluble chemical product and converted it into a slow-release, natural fertilizer that behaves much like rich compost.

Whatever the soil medium, Peters is a strong believer in the ``little-and-often'' approach to liquid fertilizing. Feeding a full-strength fertilizer solution every other week (still a common practice) provides a feast-or-famine situation for the plants in his view. ``A sudden burst of nutrients,'' he says, ``can sometimes shock a plant.''

But the occasional fertilizing approach (strong one week, none another) can work well for plants with a soil rich in organic matter. These soils are so well buffered that plants are protected from the shock of periodic application of soluble nutrients.