Two new books of considerable usefulness to gardners have been published recently. One is about all phases of gardening; the other is a how-to, month-by-month book for farm, garden and home.

"America's Garden Book -- Revised by the New York Botanical Garden," James and Louise Bush-Brown, (Scribner's 819 pages, $22.50).

First published in 1939 and revised in 1958, major developments affecting gardening made necessary a new revision by the staff of the New York Botanical Garden.

Whether you grow vegetables, flowers, bulbs or herbs, whether your gardening is indoors or outdoors, we believe this edition will contribute much to your understanding of plants," says Dr. Howard S. Irwin, chairman of the advisory committee that did the reviewing.

A near renaissance in urban tree planting, in the creation of mini-parks, green spaces, plazas, garden shopping malls and vacant lot gardening has taken place in the recent past, according to the publishers.

"The current boom in houseplants, for example, is something no one would have predicted a few years ago. It all adds up to expression of a basic human need: to have direct contact with reality as represented by the natural world.

"As the world grows increasingly crowded, however, for many the opportunity to experience unlimited landscape becomes infrequent, if not impossible.

"Gardens, therefore, whether elaborate or minuscule, or in between, have come to symbolize the natural landscape that 20th-century people are searching for.

"In other words, gardens have become more and more important to our survival as rational creatures."

Except possibly for someone very skilled and talented, it is virtually impossible to create a new garden, or even refurbish an old one, without a plan, according to the authors.

"It is much less costly to make mistakes on paper in the planning stage than to try to correct them in the landscape itself. The planning process allows decisions to be made on interrelating factors.

"If a tree is needed to shade the west windows of a living room, for example, how does the same tree relate to shading an outdoor sitting area, to bedroom windows above, your neighbor's view, spring flowers, autumn color, or septic tank leaching field where certain tree roots cause problems?"

"The Homesteader's Handbook," by Martin Lawrence (Mayflower Books, 223 pages, $7.95 paperback).

This book is not only an informative guide to the best of country-style living, but a wonderfully entertaining picture book, crammed with hundreds of nostalgic engravings from the 19th century and hundreds of tried-and-true practices for homestead and household, working farm, or backyard garden.

Did you spend $20 for peat pots to get your spring planting off to an early start? Pocket the money next year, and let this book show you how to fashion the same pots for the sod that's growing on your back lawn. That's how it was done in 1850, and the trick still works today.

Are you thinking of buying new lilac shrubs or of putting a hedge of forsythia? Why not learn to propagate your own, as most homesteaders did a century ago, and cut down on your nursery expense?

Divided into 12 sections, one for each month of the year, the "Handbook" provides general information about farm and garden work to be done throughout the year and features specific projects for each month, each described fully in step-by-step instructions.