Mabel Merchant has a gardening secret that keeps her garden practically weed-free and doesn't cost her a cent.

Her method: just roll out the rug.

Merchant, 66, a retired trademark attorney who lives in Fairfax County, says old pieces of carpet laid between rows of flowers and vegetables do the job better than mulch.

"Anything you can do in a regular garden, you can do it so much easier, so much better. . . . Anything is easier when it's carpeted," the veteran gardener said recently.

Merchant's garden covers nearly every bit of her 5,500-square-foot yard, with carpet between the numerous rows of vegetables and flowers. Strips of orange and yellow carpet blend with marigolds, pale green remnants complement the 6-foot-tall corn stalks. A long piece of bright red rug matches the cherry tomatoes. On a rooftop deck, zinnias and snapdragons in two large wooden troughs have their own small strips of light blue carpeting.

In addition to keeping weeds down, Merchant said, the carpet holds moisture during dry spells. In heavy rains, it protects the soil from packing by allowing water to seep gradually into the ground. And with wall-to-wall carpeting, she can walk in the garden without getting dirty feet.

"You can walk in it barefoot, you can walk in it in shoes, you can walk in it immediately after a rainstorm without damaging the soil," she said.

She doesn't even have to take up the rugs to water the garden. The water seeps right through.

Merchant gets most of her remnants free from a local carpet store, where workers call her when there's some old carpet available that they've removed from a customer's house.

"My recommendation to any gardener is to get a good relationship going with a carpeting place . . . that will let you know when they've got throwaway carpet," she said.

At the end of each gardening season Merchant takes up the carpet, and the pieces that haven't worn out are stored in a shed in her yard. The rugs, she said, sometimes last up to four years.

Merchant, who grew up on a farm in Tennessee and has been gardening "all my life," said she can't remember how she thought of her unusual method or exactly when she started using it.

"I think it was about 10 or 12 years ago. . . . I had some old carpeting that was going to go in the trash, so instead of using newspapers and plastic and all the things that all the gardening people told you about, I tried the carpeting. And it was so superior to anything else that I had ever used."

Merchant works in her garden nearly every day, uprooting the few weeds that manage to struggle up between the carpet strips and picking the ripe vegetables: green beans, corn, squash, celery, okra, and nearly every other species imaginable. She also grows flowers, herbs and spices.

Merchant says she doesn't have to do much grocery shopping.

"My nephew and I are living off the garden. We buy a little meat once in a while to go with it."

She sells some of her vegetables to friends and neighbors and makes flower arrangements that she markets with the help of the owners of a nearby fruit and vegetable stand. But most of the fruits of her labor she gives away.

"The secret of good gardening is sharing," she said. "If I pick my zinnias every day, then I've got loads and loads of zinnias to share with all kinds of people. I make up bouquets to sell, I make up bouquets for people that are in worse shape than I am, in old peoples' homes . . . ."

Occasionally, she finds herself making donations to others as well.

"The birds and I share the berries," she said. "But they don't eat that much. I don't mind sharing with them."