For those among you who are care about such things -- and there are many of you out there, the mail and phone calls suggest -- the onion sets have arrived.

A reader in Reston writes: "I spent about an hour on the phone calling nurseries, hardware stores, etc. I was told, as you said 'You can't plant them now.' No one had them, but one kind store said I should try the Southern States Cooperative Feed Store on Maple Avenue in Vienna, and, lo and behold!, they had them -- both white and yellow sets at 90 cents a pound."

A couple of calls to area distributors last week revealed that they are now in. In fact, one distributor -- Wetzel Seeds in Harrisonburg -- reported that they were delivering them on the very day I called. So they are in the stores.

Here is a list of the stores that Wetzel and Meyers Seeds, Baltimore, gave me over the phone. It's by no means all-inclusive, because there are probably more than two distributors in the area, but at least it will give you a place to start looking. MARYLAND

COMMUNITY PAINT AND HARDWARE, Bethesda;

FORT WASHINGTON HARDWARE, Oxon Hill;

WILLIAMS FEED, Gaithersburg;

GAITHERSBURG FARM SUPPLY, Gaithersburg;

WENTWORTH, Charlotte Hall. VIRGINIA

DeRAY'S MARKET, Woodbridge;

LORTON FEED, Lorton;

MINIHAN'S HARDWARE, Falls Church;

PITKIN'S, Dale City;

WOODLAWN HARDWARE, Alexandria;

P. T. MORAN HARDWARE, Arlington;

SOUTHERN STATES, Vienna and Leesburg;

MERRIFIELD GARDEN CENTER, Merrifield;

SERVICE STAR HARDWARE, Annandale;

FISCHER HARDWARE, Springfield;

FAIRFAX HARDWARE, Fairfax.

SEED SAVING: The same Reston reader who offered the onion-set information asked a couple of good questions.

"Can seeds from vegetables be successfully saved and planted in the spring? I picked out seeds from green pepper and a patty pan squash, laid them out on paper towelling and now they are dry. If they can be used next year, please tell me how to successfully hold them over during the winter.

"You told once how to have dried limas. Can the same be done for pole green beans? Some of my green beans have gotten too big and are not tender when cooked. Can they be dried and used as navy beans? Also, can peas be dried and used as seeds the following year?"

Most people who have compost piles can attest to the headache volunteers can become. If you throw in raw seeds as part of your vegetable refuse and the compost stays warm during the winter, come spring all kinds of little shoots come up out of the nutrient-rich heap. Personally, I encourage the volunteers. You never know what might come out of it. One friend has a fruit-bearing peach tree that sprouted from a discarded seed years ago.

The rule of thumb for seed-saving is don't bother with seeds from hybrid plants that you've grown this year. They won't breed true, or they won't produce at all, so it's a lost cause. If you're not sure if you've got hybrid plants or not, check a garden catalogue to see if the most popular plants of that species are hydrids. If so, chances are you've got hybrids. Corn is almost always hybrid. Peppers sometimes are. Many varieties of tomatoes are, especially the ones you'll be growing in a suburban or city garden. Eggplants often are. Some beans and peas are. Sugar snap peas are hybrids.

Celery, root crops and herbs are safe to save seeds from. On the subject of vegetable plants that may or may not be hybrids, I would suggest that you save a few and try them, but back up your supply with commercially grown seeds. If they bear fruit, then you're in business. Save seeds from only the largest fruit -- that will help ensure large-fruit production next year. PROMISCUOUS PLANTS: The biggest problem with saving seeds from squash plants is that squash is notoriously promiscuous and will breed with any type that's around. While you'll get true fruit off the parent plant, the offspring seed is very likely to be a mutt if you've got more than one variety in your garden. One gardener told me proudly that his entire squash crop this year came up voluntarily and the plants were huge. But when I pinned him down on what types of squash he got out of the plants, he noted ruefully that were "green crookneck, yellow-striped zucchini," and various other interesting combinations. I have something like that in my garden, and I can't for the life of me figure out what combination it is -- something like a cross between hubbard and butternut. Patty pan, I am sure, is no more selective than any of the other squashes when it comes to choosing a mate.

Drying the seeds on paper toweling is excellent. When the seeds are dry, put them in an envelope, label them and seal the envelope. Store them the same way you would the commercial seeds you're saving until next year -- that is to say, in a dry environment that won't freeze. BEAN BAG: Certainly you can use green-bean kernels as you would navy beans. However, use them fresh, if at all possible, rather than dried. You may already have noticed, if you've tried drying them, that greenbean kernels will discolor with drying. Kernels from yellow wax beans maintain a lightness of color that looks like navy beans. Fresh bean kernels are delicious, and can be boiled lightly and served in butter much like lima beans.

If you decide to dry green-bean kernels for eating or for spring planting, leave the bean pods on the vines until both the vine and the pods are quite dry and brittle. Then harvest the pods and remove the kernels just as you would pod peas and limas. BULB BULGE: The bulbs you ordered in August will be coming in now. Most can be forced for winter blooming indoors by planting them in a bowl filled with stones and water. Narcissus will need some support or they'll flop over just as they unfold wonderfully scented white blooms. Put three light-weight stakes about the width of chopsticks but taller (available at garden stores) in with the stones and connect the stakes with string so they make a little cage to surround the stalks as they get tall.

If you can get to it this weekend, tulips and daffodils can be put in outdoors for spring blooming. A bulb planter is a really useful item, and one everybody should own, because once you have planted a few of these bulbs, you'll want to add more each year. The nice thing about springblooming bulbs is that once they've bloomed, they don't prevent you from throwing in some annual seeds or plants right in with them after they've finished blooming. A few tulips or daffodils don't prevent you from getting summer color out of the same bed.