Two good books related to gardening have been published recently. One is mostly photographs of French gardens by Eugene Atget, the other is about how to garden in the shade.

"Atget's Gardens -- A Selection of Eugene Atget's Garden Photographs," by William Howard Adams, introduction by Jacqueline Onassis (Doubleday-Dolphin; 120 printed pages; $19.95 hardbound, $9.95 paperback).

There are 76 full-page photographs of gardens of Versailles, Sceaux, St. Cloud, the Tuileries, and the Luxembourg. A separate section by the author provides specific information about each photograph.

"Atget's passion for collecting his documents [that is what he called his photographs] had the intensity of a child for whom things are not yet commodities and are therefore literally priceless," says the author. "How many times strangers must have been startled by this shabby old man with his heavy camera loitering in the overgrown avenues, skeletons of Le Notre's endless vistas at Sceaux, or saw him huddled under the black shroud as he focused on the play of light over the still water of the basin at St. Cloud.

"Given the allure of the great metropolis of Paris itself, with its streets leading to endless surprises, of old houses, doorways, reflections, trees, gardens and statuary, the narcotic scent of its beauty drew him into its irresistible network and made him an addict."

To be able to look at the French garden through the eyes of Atget is one of the great gifts the artist has left us, says Mrs. Onassis, in the introduction.

This is the first time that a selection of his photographs of the royal parks and gardens of France have appeared together.

To see them together at last is unforgettable, she says. "His images communicate beauty, emotion and history in powerful harmony. Each element illuminates and reinforces the other as we follow the self-effacing, obsessed photographer on his rounds winter, summer, spring, and fall, through the gardens.

"His conquest of us, like that of his own visible world, is complete. It was beauty that he was after, and in the garden that is what is found.

"We had been concerned that the collection might appear to a viewer unfamiliar with the subjects to be an anthology of gardens scenes that all came from one place. Our concerns evaporated, for Atget's eye chose and caught with each exposure the unique essence of each place."

"Shade Gardens," by Oliver E. Allen and the editors of Time-Life Books, (Time-Life Books; 160 printed pages; $9.95).

On a steep, rocky suburban hillside near New York City there is a garden that completely blocks out the encroaching urban world, the authors say. "Winding pathways of pine needles and wood chips, informal steps and landings, and landings, and pleasant seating areas beckon the visitor into an idealized woodland. Luxurious expanses of pachysandra, periwinkle, ivy and ajuga carpet the ground. Above them rise ferns, azaleas, rhododendrons, dogwoods, yews, small hemlocks and hollies. Surmounting these are the high branches of beeches, tulip trees, a hickory and an old oak.

"From early June to midautumn, few rays of direct sunlight touch this garden, nor are they missed. The green shadows are cool and restful on a hot day, serene and reassuring. At the same time, it is anything but dull.

"Everyone who enters it is astonished and intrigued by the richness and variety of its plant life. How does it happen that shade, reputed to be so hostile to growing things could yield such a flourishing retreat?

"What many gardeners do not realize is that lots of plants not only grow in shade but actually prefer it, and that an even greater number perform well under either condition, since their need is not for the sun but for a certain level of light intensity. This gives the gardener with shade a choice of plants to suit virtually every imaginable circumstances."

Narrow city lots with deep shade surrounded by tall buildings offer a challenge, but not one which can't be met with ingenuity, the authors say. Set out tough plants -- Enlish ivies, ajuga, and moneywort -- for adverse conditions. Sink potted plants in the ground for the summer to brighten that dark corner and don't forget to spray often with a hose to remove soot or air-pollution residue.

Extra attention must be given to drainage, soil and mulch. If tree roots intrude into planting space, a barrier must be driven into the ground. Air circulation is also important, and pruning lower branches or even removing a tree or two may be advisable in some cases.

In addition to how and when to do what, the book provides an encyclopedia of plants for shade gardens. CAPTION: Picture, Wax begonias surround a shaded pool in one example from the book "Shade Gardens."; Copyright (c) 1979, Time-Life Book Inc.