THE COMPLETE SHADE GARDENER. By George Schenk. Houghton Mifflin. 278 pp. Paperback, $14.95. THE HERB GARDEN. By Sarah Garland. Penguin/The New York Botanical Garden Institute of Urban Horticulture. 168 pp. $27.50; paperback, $12.95. LEE BAILEY'S COUNTRY FLOWERS; Gardening and Bouquets From Spring to Fall. Clarkson N. Potter. 158 pp. $19.95.

AMIDST THE lavish display of spring garden books now decorating bookstore shelves are two, on shade gardens and herb gardens, that offer an abundance of lovely photographs and clear, useful advice for mid-Atlantic gardeners -- even though one author lives in England and the other in New Zealand by way of Seattle. A third that stands out in the annual bookstore border is a sumptuously photographed weekly flower diary by Long Island author Lee Bailey.

Frequently Lee Bailey's Country Flowers look better and brighter than life. But while his flower petals may bloom like the flawless air-brushed skin of Playmates and his Deep South childhood reminiscences may ramble out of control like the ajuga he warns against, his book does contain good practical garden advice, the kind friends give.

Bailey warns, for instance, against big and excessively hybridized flowers, such as thick- stemmed tetraploid daylillies which look as if they lift weights and take steroids. And he rails against some showy double flowers like the Kwanzan cherry, spectacular in the distance perhaps, as in East Potomac Park, but which Bailey finds "too excessive, almost vulgar" in a small garden.

He admits to a preference for old-fashioned flowers, rugosa roses and single-blossom cherry trees (those around the Tidal Basin are all singles -- Yoshino and Akebono). And Bailey also commends the sensible offerings of nurseries like Wayside Gardens in South Carolina and White Flower Farm in Connecticut, whose thick catalogs are both seductive floral wish-lists and informative Eastern garden books, updated annually.

Bailey and the authors of the new herb and shade garden books frequently find common ground for things like honeysuckle, foxglove, lily of the valley and malva or marsh mallow (marshmallows being the perhaps "too excessive" confection once made from its ground roots).

In The Herb Garden, Sarah Garland of Gloucestershire notes that while man may have admired flowers for thousands of years it's only recently that he began creating decorative flower gardens just to look at, "separating a garden of useful plants -- herbs -- from a garden of ornamental plants." Until about 300 years ago, she says "all plants were grown for food or medicine, or used in a symbolic way as a protection against malignant forces."

Herbs were popular in North America even with the Indians, she says, but especially in the 19th century with "the fashion for patent medicines and a general lack of confidence in physicians . . . (who) tended to rely on blood letting and the prescription of toxic substances such as mercury, arsenic and antimony." Religious groups like the Shakers, who sold a catalog of more than 600 herbal medicines in the early 1800s, were instrumental in spreading the herbal word. The current popularity of medicinal and culinary herbs she attributes in part to renewed interest in natural foods, cooking and gardening.

With handsome photographs of dozens of formal and informal English herb gardens -- glorious flowering herbacious borders filled with useful herbs and a few idle ornamental flowers -- Garland details absolutely everything anyone could possibly want to know about herbs and growing an herb garden. Except how to pronounce the word.

Perhaps one reason Americans seldom grow herbs is embarrassment. We avoid the subject or mumble the word, becaue we don't know whether to drop the H or aspirate heavily in pronouncing it. The English, who drop H's in many socially acceptable places, have carefully aspirated the Old French herbe for 200 years. Americans, according to our dictionaries, prefer a silent H. But all that is changing. The Oxford English Dictionary now generously mentions the American pronunciation, and our new Websters now says the H in herb is optional, like the O in factory or the pronunciation of tomato.

For a country that for decades has been more notorious for its (h)erbicides, Garland gives recipes for natural herbal concoctions to repel insects and animals and to fertilize or inhibit the growth of other plants, if you don't mind making pungent witches' brews of things like boiled onions, garlic, thyme, tansy and rhubarb. She prescribes fragrant walkways, with herbs planted between bricks and flagstones to be crushed under foot, suggests a maintenance-free herbal lawn (creeping thyme and chamomile are best) and medicinal herbs to rush outdoors and cut when you run out of cough syrup (rose petals, marsh mallow, thyme), can't sleep (chamomile, lemon balm or violet flowers) and have cuts (garlic bulbs, golden rod, yarrow) or stings (basil and lemon balm).

Published in cooperation with the New York Botanical Garden, her sage advice would appear to work just as well here as in England.

GEORGE SCHENK may not be everyone's Complete Shade Gardener, since, like Lee Bailey, he holds strong opinions on his subject. He lists but dislikes many of the popular trees, shrubs and flowers that do well in dappled to dense shade: all large maples, camellia (japonica), many double-flowered plants like kerria, "that floral meatball," and evergreen magnolias (grandiflora), which may be majestic outside public buildings (Justice and National Archives here in Washington) but continually litter small gardens with large leathery leaves. It "has little place in hoening." Even white birches, among the most planted of all garden trees, may be briefly beautiful in a small grove but Schenk says should be cut down for the fireplace at the age of 15 because they starve underplantings.

But he also has many likes: fall-blooming camellias (sasanqua), almost all oaks, "weed" trees like ailanthus (Tree of Heaven) and ferny-leaved mimosa, some hydrangea, "nearly the all-American, all-Canadian summer flowering shrub" and mountain laurel, "one of the choicest tall shade plants."

He recommends arborization, elective surgery that can make backyard bonsai of tall, ungainly shrubs, and offers creative advice for what seem to be unredeemable alleys and sunless north walls (sunless south walls in New Zealand and Australia, he notes).

His book is a refreshing guide to turning otherwise dark and dismal urban areas into cool, shady retreats from summer heat.