At One With the Exotic : * Retiree tends his prize orchids with skill and vigilance. The reward is a spectacular year-round crop.

Ever since his retirement in 1986, Dr. Irwin Linden has been battling disease, parasites, dehydration and other maladies he doesn’t even like to talk about.

“They come at night,” he says with distaste. “You’ve got to watch out for them.”

Formerly an Encino-based dermatologist, Linden has traded in one set of patients for a quieter, more delicate bunch: prize orchids. Where once he waged war on skin ailments, his enemies now are the slugs that sneak into his greenhouse to munch the buds on his dendrobiums. Or the viruses that render his cattleyas ugly, infectious and dead.

His primary weapon is constant vigilance--watching his plants’ appearance, moisture level, food and temperature needs. His reward is a year-round crop of flowers that smell like heaven and won him the 1993 award for “outstanding orchid culture and presentation” from the San Fernando Valley Orchid Society.

If most people associate orchids with butterfly-shaped prom corsages, a tour of Linden’s state-of-the-art greenhouse considerably expands the field.

Crowded together on benches amid the constant whir of heaters, fans and humidifiers, are some of the most exotic flowers on the planet. They resemble moths in full flight, pom-poms, lions’ heads, monkeys’ faces, even dried autumn leaves clinging fast to the branch. They come with starched sails or ruffled petals--white with yellow-stained centers, magenta with rusty depths or pale green with purple polka dots. Their perfumes are just as varied, ranging from spicy and sharp to heavily sweet and tropical.

The sheer variety of orchids is part of their appeal for Linden, who began collecting them in 1962 but got more serious when he retired. Rather than focusing on one type of orchid, he fills his greenhouse with a full complement of cattleyas, dendrobiums, phalaenopsis, oncidiums and paphiopedilums, and maintains an outdoor growing area for cold-loving cymbidiums.

“When I buy plants,” he explains, “I look for certain forms I don’t have or things that bloom during quiet months.”

Buying largely at auctions or through catalogues, he doesn’t seek out rarities, but he has, through meticulousness and patience, achieved some startling effects. One of these, an extravagantly blooming cattleya, measured more than a yard wide and had to be loaded into a borrowed truck for its blue-ribbon performance at an orchid show.

“Most people wouldn’t have bothered,” he jokes. “But if there’s a challenge, I persist.”

Ned Daniger, president of the San Fernando Valley Orchid Society and owner of the Daniger Orchids nursery in Northridge, credits Linden with more than just persistence. “He takes a lot of care with his plants; they always look spectacular,” Daniger says. “You can start with a $500 plant (but), if you don’t grow it right, it can look like a $12 plant.”

For Linden, who starts with orchids in the $10 to $50 price range, growing them right involves spending time every day watering, pruning, repotting and checking for signs of infestation or disease. He also monitors the machinery that keeps the atmosphere in the greenhouse moist, warm and breezy--akin to the ambience of a tropical jungle.

Moisture and temperature control are especially critical. Twice, in an earlier greenhouse, Linden lost his entire orchid collection when an evaporative cooler failed, resulting in a fatal level of dry heat.

In return for his pains, his plants send up a steady stream of blooms that come in waves with the seasons and hang around for months. His papery white phalaenopsis (moth orchid), for example, is blooming now and will continue for a good three months. His dendrobiums, on the other hand, may hold their pink and purple flower clusters for half the year--or even longer, in the case of his Dendrobium sonya , which is hardly ever out of bloom.

“That’s the part I enjoy,” says Linden’s wife, Barbara, pointing to a sunny kitchen window that’s always crammed with flowering orchids.

Linden agrees. “They’re beautiful. They’re my raison d’etre. “

At the same time, his responsibility for the survival of more than 600 delicate beings weighs heavily on him. “I love looking at them, I love showing them,” he admits. “But if suddenly they were gone, I think I’d say, ‘I’ve had my fun.’ ”