No plant is more associated with autumn than the chrysanthemum, which most people call "mums." Instant fall gardens are sprouting on doorsteps now, made from an assemblage of the pumpkins and potted mums available at every supermarket, garden center and roadside stand.

These tightly packed cushion mums are a lazy gardener's dream: colorful, inexpensive, carefree and disposable.

They are really not worth planting in the garden. When you buy a pot of mums in bloom, you know what the plants look like, but you don't know their chances of surviving the winter, since each variety can be the result of many breeding crosses between greenhouse florist mums and tougher outdoor varieties.

When advertisers call them "cold-hardy mums," they mean that the flowers will bloom through cold autumn weather, not that the plants will live through a Bay State winter.

If you want to try to winter over one of these potted mums, buy it now and plant it immediately. The longer it has to develop roots in the soil before it freezes, the better its chances of survival. If a plant hasn't formed a skirt of new leaves around its base, called a basal rosette, soon after it finishes blooming, you know it won't survive the winter and can remove it. If it has, don't cut down the tops after blooming, as they can help insulate the roots.

Cushion mums that survive must be dug up then when the shoots are 6 inches high next spring. The core of the plant is then discarded while the outer shoots are peeled off, each with a little bit of root attached, then pinched back sharply and planted directly into the soil.

One surviving cushion mum will produce enough shoots to fill an entire garden. Then the cuttings need to be pinched back several times to encourage bushiness until July 4, and fertilized with a spray twice a month. It's a lot of work for a questionable payoff.

Allan Armitage, author of the new "Armitage's Garden Annuals, A Color Encyclopedia" and many books on perennials, sees them as "throw-away" plants but has some tips on how to get the most from them.

"I would buy the biggest container I could find. Instead of a 4-inch size, I would get a gallon container spilling over with flowers, as beautiful as possible, to make it worth your while. The value is in the beauty, so pay $20 for a big one instead of $4 for a small one. And buy them when they're not fully open yet, with just a few flowers showing. Buy something with two or three flowers open so you know what the color is, but with 200 or 300 buds, because those are the only buds you're going to get. And don't plant them in a row like little soldiers. They are so much more spectacular in urns or groupings."

There are some kinds of chrysanthemums that make good garden plants, but they're hard to find, now that the mass-produced potted mums have taken over the marketplace.

"The chrysanthemum is a great plant that has been McDonald's-ized into something quicker and cheaper, so it's hard to find the ones now that are good for you garden," said Armitage. "There really are two groups of mums now. There are the mums at Home Depot and there are the mums that are real plants."

Once popular, the old-fashioned hardy mums that are "real plants" have been trying to make a comeback, but it's an uphill battle. Most are called Korean hybrids. They grow in graceful sprays rather than clumps and require no pinching back. Despite the name, they originated at Bristol Nurseries in Connecticut in the 1930s. Plant collectors have combed old Connecticut gardens looking for survivors and begging for a piece of root.

Though spring is the best time to plant any chrysanthemum, it's not too late to plant old-fashioned hybrids now, if you can find them.

Korean mums "never sell well. They never have," said Jean Dooley of Mahoney's Rocky Ledge in Winchester. "People are conditioned to ask for the cushion mums, which are grown by producers of annuals. It's a big business. I like the Korean mums better. They are more truly hardy and more natural and don't come out (in) cookie-cutter shapes. We get a few people looking for them every year but I don't think people realize they're a better alternative."

Wayne Mezitt, chairman of Weston Nurseries in Hopkinton, is also a fan of old-fashioned mums and sells some at his nursery.

There are several other hardy chrysanthemums

available. One, the Feverfew, is a

short-lived perennial from Europe that produces sprays of small, white daisies summer through fall if spent flowering stalks are removed. It is one of the easiest plants to grow, tolerating more shade than any other member of its family.