"Crockett's Flower Garden," by James Underwood Crockett (Little, Brown and Co., 311 pages, well illustrated in full color, $24.95 hardcover, $14.95 paperback).

This was Crockett's third book of gardening advice based on his PBS television series. He had been at work on it for over a year when he died of cancer, and Marjorie Waters, his longtime collaborator, finished it.

Like its predecessors, it is based on the month-to-month sequence of events in the Victory Garden in Boston, and is designed to be used by the novice as well as by gardeners who have been digging the soil all of their lives.

"I consider thorough soil preparation an absolute must for a good garden," he wrote. "It loosens the soil so air and water can move through. It nourishes the soil so that the soil in turn can nourish the plants. I like to do this job in the fall because it gives the added ingredients time to work thoroughly into the soil.

"The pH scale measures the level of acidity or alkalinity of the soil. This is an important aspect of soil chemistry because it affects the availability of certain needed chemicals to growing plants. There are even pH levels at which plants will not grow.The scale runs from 0 to 14, 0 being completely acidic, 14 being completely alkaline, and 7.0 being neutral. For most growing plants, slightly acid soil is best with a pH of 6.0 to 6.8. Few soils enjoy this level naturally.

"The only way to determine the pH reading of your soil is with a soil test. You can either do this yourself with a kit you buy from a garden center, or you can send soil samples to your county agricultural service for analysis. If you decide on the latter, you will receive a report detailing not only the pH of the soil, but its nutrient content and the steps you should take to bring the soil to optimum growing conditions.

"Correcting the soil pH is one job that really must be done in the fall. Lime to make the soil less acid) and sulfur (to make it more acid) both leach through slowly, and the long months of winter give them time to blend throughly with the soil.

"In sandy soils it may be necessary to correct the pH of the soil every year. In bulkier soil, where limestone and sulfur should both be fairly stable, a soil test every three years is probably sufficient.

"Organic matter is plant or animal material in the process of decay. It is hard to overstate the role it plays in soil improvement. It gives the soil substance; it creates air spaces so water and nutrients can circulate to the plants' roots; and it holds water, almost like a sponge, so that roots may absorb moisture gradually between waterings or rainfall. While I don't recommend organic matter as the only source of nutrients for soil, it does add needed elements to the soil's chemistry, and contributes to the release of soil-held nutrients. t

"There are several types of organic matter that can be added to the garden. Because it replicates nature's blend of many kinds of plant life, compost is best. Leaf mold, which is compost made exclusively of leaves, is an excellent material but it is extremely slow to decay, requiring 2 to 3 years to break down before it can be put in the garden.

"I prefer to add leaf rakings to the compost pile, which speeds their decay.

"I don't recommend adding animal scraps or fat to compost, as they tend to smell and attract pests. But any kind of plant life is fine, including grass clippings (if no weed killer has been used on the lawn), flowers, stems apple cores, overgrown zucchinis. I put this kind of material in the bottom of the composter; it decays more quickly if it's chopped or shredded first, but it can be added whole.

"When this layer is 5 to 10 inches deep, I add 10-10 or 5-10-5 fertilizer or a layer of horse manure to speed decay. Then another 5 to 10 inches of plant material, topped with a dusting of ground limestone and couple inches of soil. I always build up the sides of the layers somewhat, so there's a bowl in the center to hold water. If there's a dry spell, I water the pile to keep the decay process going.

"During the hottest part of the summer, I often cover the pile with plastic, hay or grass clippings to hold moisture in. (The compost will decay fastest in the shade because the material will dry out less quickly.) When the material is decayed to the point where it is all a uniform color and its structure is clearly breaking down, I use it as I need it to improve the soil before planting.

"If you do not have space for a composter, you will have to turn to other sources of organic matter. Manure is excellent, if you can get it. Cow manure is best, but horse manure is more available these days.

"In the fall, fresh manure can be put on the garden, but if you are doing soil preparation in the spring, the manure must be at least 6 months old or it will be so caustic that it will burn the roots of spring plantings. If you cannot get compost or manure, you can also buy organic material from garden centers. The best choices are peat moss and composted cow manure."