Onions may make cooks weep, but there's no tears to growing them

I know that onions (Allium cepa) are almost surely going to make me cry; also that they are usually plentiful and not too dear in price. Yet I would hardly consider my garden complete without its rows of this pungent vegetable.

Onion sets are among the early signs of spring wherever plants are available. They vary in size from that of a pencil eraser to fat ones as big as a nickel. About a half-inch in diameter is best. The very small ones lack vigor, and it doesn't help any to be too large.

The sets are sold by the quart measure, while plants come in bunches of 100 or more, mostly weak, dried out, and ragged. Once planted, however, they always seem to be surprisingly able to pop into nice straight plants and quickly develop into tender scallions.

There is hardly any way not to succeed with onions, if a few rules are followed. Plant your sets early, upright, and two or three inches apart. Cover to a depth of no more than one-quarter inch. As the bulbs grow they will tend to sit on top of the ground. Well, let them.

Success is determined by the amount of daylight the plants receive. Formation of bulbs depends on this one factor more than the maturity of the plant. Daylight requirements range from 12 to 15 hours of sun daily with the various varieties.

After being thinned to 4 to 6 inches apart, both sets and plants make good mature globe-type onions. Growing fast, they should be out of the ground ''before the July rains fall on them,'' as experienced gardeners will tell you.

Left in the wet soil, they are apt to rot.

Sets and plants are easily available, yet one item of concern surely may be lacking, and that is variety.

If we wish to grow different or special kinds of onions we must choose the seeds, then plant and grow them ourselves, whether the choice happens to be Bermuda, Red Weathersfield, Hamburg Red, tiny pearl pickling, or any of the other fine onions there are in the world.

Leeks (Allium porrum) are as useful as they are easy to grow.

While seeds are getting started, prepare a trench 6 or 8 inches deep. When the plants are around 8 inches tall, dig, cut spears to about 2 inches, and transplant 6 inches apart in the trench. Keep moist and, as the plants grow, draw the sides down around the roots.

This is a natural way of blanching the stalks, and if you leave one or two to blossom you can enjoy the lovely flowers as well as being assured of seeds for another year.

Shallots (Allium ascalonicum), without which many gourmet cooks could hardly function, have a mild flavor with a hint of garlic. Plants are hardy and may be left in place from year to year, or, as many growers do, simply save the smallest cloves for planting next year.

If shallots are the aristocrats of the alliums, garlic (Allium sativum) must be the black sheep.

Garlic is not generally loved for its strong, lasting flavor and odor, yet contrariwise, if used with discretion, either raw in salads or cooked in stews, it enhances almost any dish. Also, the odor, but not the flavor, is lost in cooking.

Special spots in my herb harden are thriving with chives (Allium schoenoprasum) and garlic chives. Egyptian multiplier (Allium cepa solaninum), also called Winter or Tree onions, needs a permanent place for itself. Once you have set out the merest handful of the small buttons you are in business, you might say, forever.

Multiplying around the roots, these onions will also send up a center stalk in each cluster that bears small sets called ''bul bils.'' When mature, these bend down, burying themselves in the ground to seed new plants.

Your job is to keep the patch weed-free, humusy, and moist, as well as to use enough scallions to give the new plants the room to grow.

All alliums have similar demands. All grow best in cool weather and languish in heat. This is one plant that does not mind crowding. All need rich, well-drained garden soil, plenty of humus, and compost. None can survive excess acidity, so sweeten the soil with crushed limestone along the rows. About the only pest is the onion maggot. Plant radishes close by as a lure.

Onions should be thoroughly ripe when harvested. Dig on a dry, sunny day and remove to a sheltered place to cure thoroughly. When well cured the bulbs are firm, especially the stem end.

Remove any with thick, soft necks for immediate use. Storage should be at about the freezing temperature.