Crowded onions yield big harvest

Vermont gardener Dick Raymond once harvested an almost unbelievable volume of onions from a bushel basket filled with compost-enriched soil. He planted sets in this container so close they almost touched.

Then whenever the basket looked overcrowded he would harvest every other onion - as scallions, as small ''boilers,'' and finally as mature onions.

I recalled this demonstration in intensive food production last spring after indifferent record keeping on my part left me with twice as many onion sets as I had room for. I had ordered sets from a mail-order house last winter, but omitted to make a note of this fact.

So come spring, I bought more from a local garden center, and wouldn't you know, the other sets arrived through the mail three days later. The only way to go, then, was to overplant and harvest continually.

My sets were placed one inch apart in rows roughly four inches apart. The moment the rows appeared overcrowded, every second plant was pulled for use in salads or in soups. When the ''thinned'' rows began crowding up for the second time, every alternate plant again was pulled. This left four inches between the remaining plants, ample space for that particular variety (Ebenezer yellow) to grow to maturity.

What particularly pleased me about the intermediate harvest was the size of the bulbs. They were big enough to provide us with several servings of boiled onions, which, with a little butter and liberally peppered, is one of my favorite dishes.

Planting sets is an easy way to grow onions, but not large onions. To get big specimens, you have to grow them from seed yourself, or buy started plants.

When it comes to growing king-size specimens, few home gardeners can match Iowa's William R. Windsor. Grapefruit don't come much larger than the two-pound onions that are commonplace in his garden. His basic recommendations are to start early, give the plants plenty of sun and space, and good rich soil.

If you live in the frosty North, sow the seeds in late January or early February. In about 10 weeks they will be ready to set outdoors.

Leeks, those delectable and costly onion relatives, should be sown at the same time.

The Windsor method involves digging plenty of compost into the onion bed, enriched just before planting with a sprinkling of 5-10-10 fertilizer. The young plants are set out three inches apart in every direction. During growing season every other plant is removed. This leaves six inches between remaining onions.

During the season the onions are watered regularly and given a boost with another application of general garden fertilizer and a little fish emulsion. A light mulch is spread evenly around all plants to help retain moisture and to reduce competition from weeds.

Because onion bulbs should not be cut off from the light, it is best not to apply too thick a mulch. My approach is to keep adding small amounts throughout the season - just enough to maintain the cover.

While you are about it, you might think of adding easy-to-grow chives to the garden.

Chives are grown for the onion-tasting green leaves they produce. To me, they provide both the taste and visual appearance that raises a dish of boiled potatoes from ordinary to outstanding.

Just before dinner, I go out into the garden, grasp a handful of leaves, and cut them from the plant with a pair of scissors. The leaves are readily cut with scissors into small pieces and sprinkled over potatoes or soups or stews or grilled-cheese sandwiches.

There are two types of chives - the regular, round-leaf, onion-flavored chives and the flat-leaf garlic chives that give food a mild garlic flavor. They are especially good in salads and stir-fry dishes.

Chive seed can be sown in the same way onion seeds are sown, and the seedlings transferred to a permanent garden spot. They are perennials, so once established, the chives can be lifted, divided, and replanted.

During the flowering period, chives are among the most attractive ''ornamentals'' in the garden. Rosy-lavendar flowers appear atop regular chives, clusters of snowy-white blossoms on the garlic chives.