IN SOWING seeds, we will save a lot of disappointment by using a sterilized, light soil.

Another thing I have learned the hard way is to sow seeds indoors no sooner than absolutely necessary. Any seedling can be planted out by May 15. Work backwards from that date. If it takes seven weeks for a seed to become a little plant big enough to plant outdoors, then sow no sooner than seven weeks before May 15. And so on.

Seeds vary in their requirements, and seed packets give special instructions when necessary.

Many seeds fail to grow for no other reason than they are planted too deep. When in doubt, err on the side of shallow planting, just barely covering them.

This may be the place to point out that if you admire six-inch-wide lavender zinnias, you should order them now from a firm specializing in them.

Too often the gardener wanders into a hardware store in April, sees a packet of mixed zinnias and plants them. And then complains there are too few, or none, of the sort he likes best.

It would be offensive to point out that if you want a zebra you do not order a mixed assortment of tropical fishes.No, you order a zebra. It is the same with plants. They are quite different from one another, actually, and you really should order what you want, if you expect to have what you want.

I do hope this observation will not result in a spate of inquiries where to buy zebras. (Though they are quite obtainable.)

Occasionally, by the way, I do really stupid things. Most recently I ordered the rambunctious rose, 'Polyantha grandiflora.'

It grows to about 35 feet and should do nicely roaming over a large old dead oak. Needless to say, I have no such place to grow it.

If it arrives (always problematical nowadays) and if it grows (which is not certain either), then I shall spend the rest of my life trying to keep it to a third of its natural size.

Why do gardeners do such things?

Because they are possessed. That is why.

I am very fond of the restrained climbing rose (a hybrid tea) 'Suter's Gold,' which opens yellow flushed with orange-red and promptly fades to chamois-cream, and the bloom is rather shapeless once it opens.

It does not bother me in the least. I admire it tremendously. For me however, it is taking its own sweet time to climb. As many hybrid tea climbers do.

The thing to do, of course, is give it a five-inch mulch of rotted manure now and water it faithfully all through the growing season.

It really does us no good to complain, when we know quite well we have neglected extra watering in the hot season.

This year I intend to water my 'Dortmund' heavily, too. It is a fine five-petaled scarlet climber of slight scent and spectacular nature when happy.It may be grown as a large sprawling shrub, eight feet high and wide, or as a climber. But it needs good feeding and heavy watering to inspire it to send up those vast thick shoots from the ground, which is what we want all climbing roses to do.

When we first plant them, we expect no progress to speak of the first year and not much the second. But the third year, if we have been faithful in our care, we should be rewarded by tremendous stems that reach 10, 12 or 15 feet, depending on the rose.

Once, years ago, I planted a bush (not the climbing sort) of the white tea (not a hybrid tea) 'White Maman Cochet.' The second year it shot forth stems 30 feet long. I measured them. This was not desirable in a rose bed. Either the nursery sent me the climbing form by mistake or else my bush sprouted into a climber. I mention this to show that once climbers get going, they indeed go.

We gardeners are all careful, needless to say, not to acquire a rambunctions climber when we have space only for a restrained one.

A year or so ago I recommended the single white climber, 'Silver Moon,' to a friend, to grow up an oak.Thus far it has sat there. But I shall yet be vindicated, I imagine, because this rose is capable of climbing oaks.

Like most roses, it is very beautiful; but it only blooms once a year and has no handsome fruit, and its beautiful glossy foilage can be made ugly by blackspot. With all those faults, it is still one of the finest of roses for growing up old trees; but in such locations it needs very generous treatment indeed. Perhaps my friend will read a slight reproach in this.

Don't you think it is rather odd that the season after a gardener plants something that is a bit miffy, the season is precisely wrong for that particular plant?

I am determined, and have been for many years, to succeed at last with the common palmetto outdoors.

But again this winter, I do not think it can pull through this disgusting snow and ice. It can take the cold. It can take the ice. But not week after week.

The great trouble, of course, is that this city is entirely too near New York, Boston, Montreal and the North Pole. Over the decades, weather records show we have a mild climate. But let anything go slightly wrong with some cloud over Duluth, and all Canada descends on us.

One year, to cite another common woe, I had had enough of tomatoes that fell victim to verticillium every year. So I wrote off for an utterly foolproof sort, developed in Mississippi (which is the verticillium capital of the world) -- and sure enough, no verticillium among my tomatoes that year.

Unfortunately, that was the year the season was perfect for even the most delicate tomatoes. People who paid no attention to anything had tomatoes suitable for catalogue covers.

My ratty little tomatoes were free of verticillium, as advertised, but not much larger than golf balls.

Nowadays there are fine tomatoes bred with resistance to various diseases, and they are worth growing.

It is unfortunately true, in general, that every plant has some faults.

Just this week I was sorely tempted by 'Mrs. Edwards Whitaker,' one of the loveliest of all blue water lilies, with flowers more than a foot in diameter. She has just the poise, just the air, just the total package of ultimate elegance and beauty, despite her size.

But of course she does not bloom as freely as other blues. So conspicuous is this failing that I was not surprised to see one nursery head right into the defect and claim, "Free bloomer." A flat lie, of course; but at least it shows he is aware there is some question of how freely the lady carries on.

It reminded me of those cigarettes I once smoked, very popular in Louisiana, that would make a stone sphinx cough. They were always labeled "extra Mild."