The art of molding chrysanthemums

Ask Ken Johnson about chrysanthemums at this time of year and the director for horticulture here at Callaway Gardens' Sibley Center is likely to show you thousands of them, massed in such quantities that the sight almost takes your breath away.

He'll point to varieties so brightly colored that to view them under a Georgia sun sometimes requires dark glasses for comfort.

In particular, he'll point out the mound-shaped Golden Dream from Japan. And then, even while his enthusiasm for the fall flower is at its height, he's likely to tell you that when he looks at a chrysanthemum he often sees ... ''a lump of clay.''

Clay? Yes, because in Mr. Johnson's hands a chrysanthemum can be molded and shaped into almost anything he wants. Here at Callaway, he has mums growing in containers and out of the sides of containers so that they look like huge yellow , orange, or lavender balls. Others spill out of their container in a cascading torrent of color all the way to the floor perhaps five feet below. Still others form topiaries or are espaliered.

There is very little you cannot do with a chrysanthemum. In the Johnson view, it is a ''most obliging plant.''

On the other hand, a chrysanthemum needs constant training. Even the massed, conventional plantings of chrysanthemums at Callaway Gardens are as spectacular as they are because of regular pruning.

In producing this festive fall parade here each year, Mr. Johnson and his staff raise some 18,000 chrysanthemum plants. Such is their skill that fewer than 15 of this total are ever lost in a season.

In many ways the breathtaking displays of Callaway can be achieved at home, if on a lesser scale, Mr. Johnson explains. Bringing chrysanthemums to the state of near perfection seen here requires consistent work, but otherwise the rules ''are pretty straightforward,'' he says.

These basic rules can be defined as: good soil, plenty of sun, weekly feeding , and consistent pruning - say, once every 8 or 9 days. - to develop a compact plant that can support a mass of flower stems come fall.

The Callaway horticulturist suggests that while many home gardeners have developed great soil and feed their plants regularly, a vast majority fail to produce top-flight mums for two primary reasons: (1) a lack of sun and (2) a marked reluctance to prune properly. They plant them under trees or alongside walls that shade them for part of the day. Nothing less than 8 hours of direct sun will do for mums and, in fact, they need more than that to reach perfection.

Here at Callaway Gardens a teaspoon of time-release fertilizer (14-14-14) is placed in the planting hole of each mum. In addition, a 20-10-20 mixture of soluble fertilizer (one tablespoon to a gallon) is fed once a week. ''We keep them at the dinner table all season long,'' says Mr. Johnson with a smile.

The plants are pruned once every 8 to 9 days, he adds. This simply means pinching out the tops of all the new shoots to encourage branching.

Is there any drawback to growing mums? Only one, according to Mr. Johnson: ''We do all this work for a show that lasts only 6 weeks'' (early October though Thanksgiving here at Callaway).

Here is the Johnson method for forming a magnificent cascade of flowers - a waterfall of color - using chrysanthemums:

In a 5-gallon pail he places 3 single-stemmed, tall-variety chrysanthemums, 8 to 12 inches tall, and allows them to wilt from lack of water.

At this stage the now-pliable stems are readily bent over and loosely fastened to a frame made from sturdy mesh fencing. The soil is then soaked with water, and the stems stiffen up in the cascading position.

From now on the plants never go without water or regular feeding, but the growing stems are constantly strapped down while they are still soft and pliable. Side branches are similarly trained down.

When the tips reach the desired length, they are pinched back to stop any further growth. This pruning, in turn, encourages further side branching, which is also trained down. The result is a mass of downward-growing or cascading stems that produce hundreds of upward turning buds at flowering time.

When the flowers start to open at Callaway, the cascading plants are loosened from the wire frame and moved to one of the public display areas. By this stage, of course, the cascading position of the stems has become permanent, and there is no further need of the wire frame. At home the cascade could be left where it is or moved somewhere else in the garden or even indoors.

That's one of the beauties of the chrysanthemum. While it demands considerable sun during its growing and bud-forming period, once the flowers are well formed it will continue to display its beauty unaffected by shade.