Can we garden our way out of this hole?

Just a few years ago, the road to riches was clear. We could all sit on our porches drinking mint juleps while our houses appreciated 30% a year.

Now, our houses are falling in value by 30% a year. Forget about them. The real money maker, it turns out, was always our backyard. By planting a vegetable garden, we can slash our food bill while eating healthier.

Lettuce is seen growing as first lady Michelle Obama, not pictured, plants herbs in the White House Kitchen Garden. Associated Press

Michelle Obama has put a vegetable garden on the grounds of the White House. Sales of seeds and plants are soaring. And pro-garden groups are churning out studies that show huge paybacks on investing in a home garden. The nonprofit National Gardening Association just produced a study -- sponsored by ScottsMiracle-Gro Co. -- that found the average family with a vegetable garden spends just $70 a year on it and grows an estimated $600 worth of vegetables.

George Ball, chairman and CEO of seed giant Burpee, can rattle off the savings for dozens of homegrown crops. Green beans will generate $75 worth of crops for each $1 you spend on seeds, Mr. Ball calculates. Even the lowly potato will generate $5 of spuds for each $1 you invest in seeds.

Does it all sound too good to be true? Depending on your situation, it may be. Neither Mr. Ball nor the National Garden Association study focus on how much you may have to sink into your garden before you can grow anything.

If you're starting out, you'll need tools to till the soil. You may have to terrace your land or build raised beds. You may need a fence to keep animals out. Many of these are onetime expenditures, but they can cost a lot more than seeds.

Mr. Ball replies that most people will still save money by growing their own vegetables. He says that items like fences and tools last for years, and their costs should properly be amortized over the life of the garden. In fact, he believes his seed-payback ratios understate the true benefits for growing your own "because of the vastly superior produce you'll get" in a home garden, compared to what you get from a supermarket.

I know about the steep upfront costs firsthand. My wife, Clarissa, has become quite the gardener, growing mainly flowers but some vegetables. In each of three previous houses we owned during the past 14 years, she invested thousands of dollars in exotic plants, containers, irrigation systems, fertilizers, soil amendments and growing lights for the winter.

So when she announced recently that she was going to plant a vegetable garden at our current house in New Jersey, my first thought was: "How much is this going to cost me?"

To which Clarissa replies: "Forget about the cost. It tastes good." This year, she's planning to plant rare heirloom vegetables that you can't get in the store.

At least our soil is good. Let's say you live in Chicago. The city has a heavy clay soil, so many residents opt for raised vegetable beds, says Ron Wolford, who works at the University of Illinois Extension.

Building an 8-by-4-foot raised bed and filling it with compost and soil will run about $80, Mr. Wolford figures. Buying a couple of tomato plants and six pepper plants to put in the raised bed will cost you another $15 or $20, he calculates, putting your total cost near $100.

A lot of people start gardens and give up when the going gets tough. "I get a lot of calls in the spring from people who want to start gardens and can't wait to get started," says Mr. Wolford, who grew up on a farm in Peoria, Ill., where his family grew its own produce. "But when it comes to July and August, and it's 95 degrees, and there's insect problems, it just goes to pot."

Gardening is hard work. I saw this when I lived for a month with a French family in 1976. Roger Martin, a retired stone mason, had a huge garden in the back of his house in a far northern suburb of Paris. He kept a little notebook where he logged the hundreds of kilos of strawberries, stringbeans, lettuce and other produce he grew every year.

Mr. Martin spent his mornings toiling in the garden. All the vegetables on the family's dinner table came from the garden. What we didn't eat or preserve was fed to the rabbits along with leftover bread. The rabbits were eventually slaughtered and eaten, too.

Will most Americans take their home gardens that seriously? I doubt it. Can you still save money with a garden? Absolutely.

The trick is keeping your capital costs down. Lori Bushway of Cornell University's Department of Horticulture says a garden can be as simple as digging up a few square feet of your lawn and sprinkling lettuce seeds in the dirt.

Most anywhere grass can grow, lettuce will grow, she says. What about fertilizer? Not needed. What about weeds? Plant the lettuce tight enough, and there won't be room for any. This simple garden will fill salad bowls for about six weeks. Ms. Bushway advises planting four square feet of lettuce per person in your household.

"You can easily triple your investment," she says. That's better than any of my mutual funds have done lately. Break out the olive oil.