THE DECREASING size of gardens both dismays and encourages me, since it means fewer and fewer gardeners with space to grow a representative assortment of glorious plants, but it also means, for the first time in our society, that millions now have gardens.

Gardens are part of civilized life in America really for the first time; that is, part of the daily background to life for almost everybody that has a house, and for many who live in apartments and have devised balcony or courtyard gardens.

Serious (fanatical) gardeners for the past two centuries have focused on England, because that country's climate, however ghastly to live in, yet permits the growth of almost everything.

Nothing is more instructive than the change, within the past generation, of the gardening in those islands as reflected in the unrivaled magazine of The Royal Horticultural Society.

A "small" garden was one of 2 1/2 acres, say, with a couple of 200-year-old cedars or Scotch pine or elm or oak, and a little tuft of woodland for the accommodation of a few (perhaps 300) azaleas, rhododendrons, andromedas and wild gingers. Naturally there was a lawn of half an acre, and a ter-race of Cotswold stone ample to seat 40, and maybe a separate iris and rose garden, and a mixed border of perennial plants -- delphiniums, phlox, the usual things -- combined with clumps of yuccas, phormiums, a few tender shrubs against the wall, such as solanum, ceanothus, and the like.

Often there were only two gardeners or even just one to take care of it, plus the owners, of course, who increasingly did more of the work.

That is what a small garden was.

Increasingly they have gotten smaller. A two-acre garden now is thought rather on the roomy side. Few can afford to take care of more, and even a garden of an acre is now full of labor-saving policies -- an increased admiration for meadows and relatively shaggy woodland, and very little clipping of lawn edges.

Water gardens (which involve less upkeep than anything else in the horticultural world) are more popular than formerly, and a greater proportion of space is given them, I sense.

In the flower border itself, once sacred only to soft perennials that die down completely in winter, shrubs have moved in. Mahonias, junipers, hollies, box, yew, viburnums, osman-thus -- any number of quite substantial woody plants have increasingly occupied space once given to michaelmas daisies, doronicums, carnations and delphiniums.

Peonies are far more important than in the past, along with hemerocallis or daylilies, because they are two first-rate showy perennials that require virtually no attention in spraying for bugs, nor frequent lifting and thinning out.

Contrast the iris with either of those. It requires attention throughout the year, every year. It is relatively less important, then, than formerly, although it should be clear to anybody that no other flower equals it in beauty.

So all this is part of the gradual change involved in smaller gardens. Even so, I never expected to see the day in which the RHS would photograph a garden 17 feet square in London.

I never expected, myself, to plan a garden 12 by 14 feet, to show one way that space might be used, and to write about it in this space, yet I did.

Though I am no garden designer, I thought it important to show that even so small a space could include stone pavement, an arbor, a tank for fish and water lily, and an assortment of living blooming plants for interest through the year.

Somewhat to my surprise, the plan was followed. I remember it was hard to persuade the owners that cut stone was worth the difference in price -- after all, the thing was so small they could have paved it with sapphires and it wouldn't have made much difference.

It is depressing to see small spaces like that, back of congested city rows, paved solid with nothing more than a few geraniums in pots hanging precariously from the fence or wall. What kind of garden is that?

No, the garden should be full of variety, no matter how small. I cannot argue against a garden in which good-looking concrete contrasts with a mass of ivy here, a patch of cobbles there, and some gray sprawling junipers yonder. These are excellent elements of a garden, and the result may be satisfying to any esthetic eye. But how barren, really.

Couldn't there, even in tiny town gardens, be color in spring, summer and fall? And fragrance?

Couldn't there be some provision for the normal delight of dipping fingers or toes in a pond? The life of the family dog, incidentally, is enhanced by any pool of water, although I know sad cases in which retrievers disturb water lilies as they slop through twice a day inquiring after ducks.

Of course it depends on the gardener. Some say they are satisfied with something that is green, affording pleasant contrasts and a place to sit, and they want no more.

But surely this is usually a case of settling for too little. There are many tensions in gardening -- the climbing rose that needs pruning, the iris stalk snapped off, the lily bulb speared through, the awful eelworm that strikes the phlox, the grim slug and fierce cutworm that assault the infant clematis.

Often people think, "Well, I am simply not up to that sort of hospital."

But life and vigor are the common qualities of plants, and nobody should be put off by supposing terrors lie ahead. They do not.

In religion, psychiatry, medicine, art and business there may always be a temptation to short cuts. Some new movement, some new gimmick, will assure instant enrichment, cure and depth of soul.

It has never worked that way, of course, least of all in gardens. Sometimes I think Gertrude Jekyll did unsuspected harm in saying gardening is painting a picture with plants. As she did it, with her profound knowledge and love, the result was incomparable, but possibly she did not emphasize enough that gardening is not merely a picture, but also the cyclic celebration of growth.

The look of May is by no means the look of June, though both are flowery months. The paved garden with a little ivy may be a flawless picture, but it in no way satisfies the desire for tulips sprouting, blooming, withering, and returning next year -- followed by irises fanning, surging, branching and resting.

All through the year there must be developments to watch with excitement, not merely static pictures to applaud, month after month, year after year.

Now a great problem, I cannot help observing, is that many people -- possibly even some architects -- understand very well the importance of a good-looking effect, but are by no means sure exactly how to go about planting a small garden for little recurring climaxes.

It took me a while to comprehend that some excellent citizens are no surer of the sequence in which plants bloom than I am of the mysterious connections between carburetor, starter and the general gizzardry of a car.

We should continue, therefore, in two fairly specific additional articles, to say how the small garden is framed, and how it is ornamented.

The framing, next week, will deal with enclosing the space, and I will omit such fantasies as high walls of superb old brickwork or ashlar lime-stone with clairvoyees of wroughtiron. Instead we shall contemplate plants against fences, and the general floor plan -- how much to pave, how many shrubs and why.

And then, later, the ornaments. Not necessarily bronze urns from the 17th century or marble vases from the 1st, but specific plants as major track-stopping ornaments, and a nod to water basins though not too much, as we are forever going on about them anyway, and a simple statement of when the chief flowers bloom and how to relate them to their predecessors and successors. In this way we may avoid mere agreeable correctness achieved at too great loss of thrills.