Four very good books related to gardening - from an encyclopedia by a noted authority to a book about planting according to the moon - Have been published recently.

"Wyman's Gardening Encyclopedia," by Donald Wyman (MacMillan, 1,221 pages, illustrated, $19.95).

Donald Wyman was horticulturist at Harvard University's Arnold Arboretum for 33 years and is now horticulturist emeritus. A former president and director of the American Horticultural Society, he has received highest horticultural awards in the United States and Great Britain.

The encyclopedia, a revised and expanded edition, is an excellent guide to all aspects of gardening, indoors and out, covering gardening techniques from greenhouse management to tree surgery.

More than 9,500 plants are described with information on hardiness, ornamental value, cultivation, propagation, diseases and pests. There is a color section of 62 photographs plus revised black and white pictures, 108 photographs and 206 drawings.

"Wildflowers," by Mary Ferguson and Richard Saunder (Van Nostrand Reinhold, 190 pages, illustrated in full color, $19.95).

Mary Ferguson has been recovnized internationally for her wildflower photography. Richard M. Saunders retired recently as professor of history at the University of Toronto and now spends much of his time as a naturalist and nature photographer.

The purpose of this book, say the authors their introduction, is to show the beauty of some of the common and rare wildflowers to remind us of those we might look for in spring, summer or fall.

Each flower is accompanied by a descriptive text providing important botanical details as well as other information, both fact and folklore.

"The Complete Book of Miniature Roses," by Charles Marden Fitch (Hawthorn, 342 pages, illustrated, $12.95).

Fitch, an outstanding horticulturist, has grown minature roses for more than 20 years, and his book is indispensable for hobbyist or expert.

Grow minatures indoors for the winter, he suggests, to enjoy their delightful colors, perfume and delicate beauty, and when spring comes plant them outdoors permanently. When fall arrives, buy new ones, with exciting color blends, different growth styles and variations on miniature charms.

"Planetary Planting," by Louise Riotte (Simon and Schuster, 352 pages, illustrated, $4.95, paperback).

"I have planted under the signs and in the correct phase of the moon in my own garden for 30-odd years," says the author. "Often I have seen my plants prosper and grow while those in other gardens failed or produced but a small crop."

Last spring, for instance, on a day when the garden was a sea of mud she waded in, barefoot, almost up to her knees, to plant corn seed. Her husband stood on the bank laughing at her. "That day was the right sign and the right phase and I was bound and determined to plant," she says.

Later, each stalk produced an average of two full-sized, sweet, delectable ears of corn.

"Yes, I believe in moon gardening." she says. "That is the Why of this book."