Whatever the reasons, it's probably not about saving money. That $28-million would go pretty far at a farmers market.

"People don't garden to save money, they do it for good food," said Bruce Butterfield, research director at the gardening association. "If they think there's going to save money, they'll be disappointed."

Nevertheless, it seems like savings should be possible, especially if you don't count the hours of labor you put in.

One gardener who has tried and written about it is John Mertus, a hobbyist and mathematician from Rhode Island. Mertus scrupulously recorded every penny he spent in his garden, including energy and water used, and the amortized value of his tools. Then he comparison shopped at two different groceries for the food he grew, counting and weighing along the way. Finally, he had a bottom line: He spent $227 total, and basically broke even.

But that was a worst-case scenario. Mertis believes that he earned a $268 profit, by analyzing it like this: He "saved" because money saved in the garden is tax-free: $250 worth of produce is like $425 worth of pre-tax salary, he argues. And he saved more because he was eating high quality, home-grown organic produce.

If, instead of comparison shopping at his local bargain-priced Stop and Shop for conventional produce, he comparison shopped at the expensive organic foods market, he would have saved more. He "saved" money by growing unique varieties and unusual produce that would cost more than basic tomatoes and cucumbers at the local market. And he saved money by dining out less during the produce season.

Mertus works on a larger scale than the typical home gardener, who will spend about $58 on his vegetable plot this year, according to Butterfield. But the same money-saving ideas apply. Here's how to get the most payback from your kitchen garden and yard:

- Plant trees first. A well-landscaped yard with trees can raise the price of a home by 30 percent, according to the admittedly not impartial American Association of Nurserymen. And it takes years to grow a tree. So buy them when they are small (or get them free from the National Arbor Day Foundation, (http://www.arborday.org), and watch them grow.

- Fill in with perennial plants that will come back year after year and keep those annual flats of flowers to a minimum. Two sources of very cheap mail-order perennials are Bluestone Perennials in Madison, Ohio (http://www.bluestoneperennials.com, 800-852-5243) and South Creek Nursery of Palmyra (www.sexybloomers.com, 315-597-5330.) South Creek Nursery sells many plants - including herbs - for $1, but has run into drought problems and allowed its Web site to get out of date, so call before you order and put your purchases on a credit card that won't be billed until the plants are shipped.

- Grow herbs, and start from seed. A few sprigs of basil or tarragon can cost several dollars at the grocery, but many of these plants grow like weeds, and look good even in landscape gardens.

- Buy your seeds at the end of this season for next year. Mertus goes seed shopping in June and July, when home centers are clearing out their seed displays. You can buy a pack of lettuce of bean seeds for 10 cents, he says, and hold them in a sealed plastic bag until next year. A second choice: Many stores hold seed sales on the Martin Luther King holiday weekend.

- Trade seeds, through the National Gardeners Association (http://www.nationalgardening.com). Find someone who is growing what you want and send them some seeds that they want.

- Grow gourmet. Beefsteak tomatoes and bell peppers crowd many store shelves in August, but you'll still pay premium for Italian style peppers, grape tomatoes, white eggplants. Yet they are no harder to grow.

- Grow fruit. Depending on where in the country you live, currants, blueberries, raspberries, apples, peaches or pears (papayas if you're reading this in Hawaii), can be pretty self sufficient, once they are established. But they'll yield expensive, delicate fruit year after year, says Mertus, who offers this final bit of advice, only slightly tongue in cheek: "Burn all your catalogs when they come, that's the best way to save money." Gardeners waste the most in the dead of winter when those glossies come in the mail, whetting their appetites for the latest varieties and unusual species.