TWO YEARS ago some of the willows barely lost their leaves but this winter they have been bare three months or so, yet both were normal winters.

Ordinarily a garden pool 18 inches deep does well enough for the wintering of goldfish outdoors, in this climate, but the past two winters the ice has gone 24 inches deep, or more.

Usually the mockingbirds are singing madly in February. This year it was mid-March before they found much to sing about, and a friend in the county tells me the purple martins are already some days late arriving - they cannot manage until there are adequate bugs flying about.

Such examples show the impossibility of predicting when certain early flowers will bloom. By late April, the season is predictable, but in late winter and early spring a few degrees one way or another can make a difference of three weeks in blooming time.

No doubt Easter, with its flamboyantly variable date, reminds us not only of the phases of the moon (on which that date is based) but of the changing tides of spring, the most treasured of all the seasons and the least predictable.

There is much danger the gardener will fall quite overboard in the spring and devise a garden stuffed with early flowers to the exclusion of everthing else.

in very small gardens back of row houses it makes sense to go a bit heavy on snowdrops, crocuses, early bulbous irises (especially the brilliant yellow I. danfordiae), blue starflowers (Brodiaea uniflora) and early scillas and anemones. Even in tiny gardens, August will come, so one should not put all his eggs in the spring basket.

Such flowers show up best when seen on intimate terms, and I cannot think of anything more likely to melt even a flintheart than a batch of these small flowers holding their annual orgy the last days of winter.

But in ordinary gardens it works best to choose some spot facing south, preferably near a walk or a door where, the gardener often comes and goes (the better to see these flowers as much as possible) and to plant them thickly. If the house faces south, say, several hundred such bulbs can fit nicely into a space smaller than the average living room rug. There they make a modest show (the gardener will think it gorgeous, so starved is he for white and gold and wine-purple and milky blue, etc.). To me this is a better plan than dotting the early bulbs about the garden, where the effect is diluted.

Over the years I notice gardeners scrimp in several areas where they should be generous:

Fences, walls, paving, water basins or lily pools, and small garden structures all cost money. Besides that, just try finding somebody to do the work. Ha.

Nevertheless, it is almost always a mistake to economize. No matter what they say about democracy (and it is a source of endless gas in public speaking) a garden is best enclosed on all sides. There is no reason the garden cannot be open to the public when it looks particularly good, but it should have the air of being secluded and private.

Cats, needles to say, cam climb anything but fortunately most of them are slothful by nature and will not bother. You will have fewer cats with a stout six-foot fence or wall than without it, and fewer children engaged in cavalry charges.

Now a great many gardens have no place to sit. A structure as simple as some four-by-four wood posts and rafters adorned with vines will serve well, especially at the end of the main walk. Clematis, grapes, roses, akebias, birthworts, honeysuckles are among the obvious and lovely creatures for festooning the place.

Just here let me say that few gardeners make their patios large enough. I am not much of a patio person (more an arbor type, possibly) having endured more than my share of stinging bugs, wet dogs, slimy bricks, arctic drafts and mysterious gazpachos on other people's terraces.

But patios make sense, for all that, and many of them are too small. Eighteen by 25 feet is a good size for starters. Of course in tiny gardens that would take most of the garden, so you have to use judgment; but in general the patio is smaller than it should be for comfort and use.

Let me say something about plastic lily pools. First, I like butyl rubber better than vinyl linings, and I like fiberglass better than either. Unfortunately the rigid weatherproof fiberglass is not only expensive, but the pools are usually much less than 24 inches deep, which is the shallowest I would like. They also come in strange shapes since, I imagine, they are all designed by Californians, nightclub operators or forest folk, none of whom understand the rectangle, the circle or the square. What is desired is a six-by nine-foot rectangle 24 inches deep, but try finding it.

Anyhow, enormous attention should be paid to the coping, especially with vinyl or other light plastic sheets. Where the plastic meets the earth usually looks extremely bad.

Concrete, as everbody knows, is the best material for a basin or pool, but it should be poured as one mass. Nothing would ever persuade me to build a pool of blocks or bricks, and I don't care what they say about waterproofing. The state of American technology may be all right on the moon or in wristwatches, but I do not trust any American I ever met to build anything waterproof if it has joints or seams in it.

Another of the commonest errors (along with scrimping on fences, pavements, pools, arbors) is failure to think about winter. That is understandable; I can hardly force myself to think of it.

A few evergreens are necessary. Yew, holly, juniper, false cypress, mahonia, photinia, box, the hardier varieties of sweet olive, camellia and ivy are all admirable. There should be enough to prevent the gardener thinking, when he looks out in January, that he is in Gary, Ind., or Tysons Corner. A few conifers and other greens will do much to distract one from the general ugliness of light poles, wires, monstrosities on the horizon, etc.

In town gardens I would avoid large conifers, and hemlocks in particular are loathsome unless, of course, the gardener wishes to ponder funereal visions and unrelieved gloom the rest of his days. The great evergreen magnolia is also oppressive and foul in small gardens. Yew and box and hollies are less overpowering, and much easier to keep under control.

The Japanese holly, by the way, is almost always a wretched plant. This city, like most others, is a veritable museum of decrepit Japanese hollies, which may well be the worst of all plants for clipped hedges, and therefore among the most widely used. I mention this so that when you are ultimately revolted by that plant you will not say I didn't tell you.

To grow a rose up a tree (this does not follow, but several have inquired) is no great problem if you use the right rose and the right tree:

I have seen 'Silver Moon' growing up oaks, but there is no point trying to grow any rose up an elm, maple, Pecan, yellow poplar, unless the tree is sawed off at the top which rather defeats the point of having the tree.

Old apples, sawed-off maples - the ideal fate of a maple - hawthorns, crabs, lawson cypresses and so forth may be adorned with roses easily, though the gardener must remember it is the devil's own work to get dead wood out of a rose up a tree. Also, the rose must be far enough from the trunk to get a bit of food and air. Six feet out is not too far. You would wish to use a rose of vigar, like 'New Dawn' and not expect a pillar rose ('Joseph's Coat,' say) to fling itself about in the branches.

Some have recommended planting the rose in a plastic liner. I would no dream of such a thing. Who knows why gardeners so love to do thinds that are complicated, chancy and insane? How does the water drain away from the rose roots in a plastic liner? Really, the things somebody will think of.

Roses are especially pretty in hollies. The holly (whether native, English or Chinese) is well behaved. All you do is make sure the rose gets a bit of extra manure and extra water for the first few years. Do not expect much to show for your efforts for four years.