Has a soil-testing lab ever suggested that your gardening outfit should be a hazmat suit? Do you have a weed problem (and not that kind of weed problem)?

One last question: Are you ready to learn about a transformative garden technology that could change your life — for less than $100?

No? I wasn’t sold either when I first heard about a peculiar food-growing method called straw-bale gardening. Like me, you might have missed the Facebook page, “Learn to Grow a Straw Bale Garden,” which has registered an unlikely 21,000 “likes.” What you’ll soon learn there is that a straw-bale garden is a garden that has been grown in a straw bale. Really.

I’ll admit that my confidence was not necessarily fortified when I discovered that the movement’s leading evangelist, Joel Karsten, also markets novelties and teaches adult-education classes on better eBay-ing. The garden catalogs are fat this time of year with spendy gimcracks that promise to revolutionize the tired old routine of putting seeds in the earth and waiting for them to grow. Upside-down tomato towers. Compost tea brewers. I categorize these consumer items as solutions in search of a problem.

Yet I recently had the opportunity to read Mr. Karsten’s new book, “Straw Bale Gardens” (Cool Springs Press) and to spend a day at his home just north of St. Paul. I also chatted with a handful of contented kitchen gardeners who have hauled straw bales into challenging urban environments. And I’m happy to report that Mr. Karsten doesn’t appear to be selling a bill of goods. In fact, he isn’t hawking any merchandise, other than the book and a self-published pamphlet, “Straw Bale Gardening.” (To date, he has distributed some 50,000 copies of this short tract, between print and e-books.)

But for all the novelty of straw bale, in essence, “it’s a different kind of container garden,” Mr. Karsten said. He was sitting at his dining room table, munching a piece of coffee cake that his wife had baked for the occasion.

If you’re not the least bit country, a bale is one of those densely packed, rectangular bundles that you might see in a Halloween display. A straw bale typically measures about 24 by 42 by 18 inches, and costs $5 or $6. (Surprise: you may pay twice that in New York City. See accompanying article for shopping advice.) In other words, a straw bale is often literally cheaper than dirt.

It was Mr. Karsten’s clever notion to condition the bale with a little fertilizer and water, creating a kind of instant compost pile. “The crust of the bale decomposes slowly,” he said. This is the vessel. The inside, which decays faster, “is our potting mix.” Stick a soaker hose on top, then plug some tomato seedlings into a hole gouged out of the straw. Time to wash the taint of barnyard off your hands: you’ve got a vegetable garden.

The advantages of straw bale are legion, Mr. Karsten said. The straw, having been harvested for its wheat or oats, should be clean of weed seeds. What few weeds do appear in the loose mix — we’re talking one or two — can be plucked out easily. The bale stands thigh-high; there’s no need to bow down before a cabbage. And the residual heat from the bacterial decomposition may allow you to start planting a few weeks earlier than usual. (Just drape some plastic over the top.) At the end of the growing season, you’ve got rich compost to add to your flower pots or beds.

That, my friends, is the hard sell.

BUT I’VE GOTTEN AHEAD of myself. When Mr. Karsten, 43, first planted a straw bale, he wasn’t planning to rewrite the annals of kitchen gardening. He had studied horticulture while playing Division I football at the University of Minnesota. But happenstance led him into the import-export business, which somehow veered into licensing and direct marketing toys. (Some careers are carefully cultivated; others spring up as volunteers.)

Mr. Karsten’s hit was (and is) the Gyro-Kite, a heli-kite that works by the principle of autorotation. “Over the years we’ve sold over a million of them,” he said. “We did an infomercial at one point: Call 1-800!”

Those were the years of fast food and takeout, Mr. Karsten said, an unhealthy departure from the fresh vegetables he remembered tending in his grandmother’s garden. “When I moved into this house,” he said, “I finally had a place where I could put down roots, literally.”

But the house, sited on the edge of a swamp, had been built on construction fill. The densely packed dirt “didn’t look like that soil back on the farm,” he said. The scrap heap of memory provided an alternative. Mr. Karsten recalled “great big weeds and thistles” that would climb out of the busted straw bales he had heaved against the barn.

And so he organized a little experiment. He enlisted his father to deliver a few dozen bales from a neighbor’s farm. One row of straw he treated with scoops of balanced lawn fertilizer, another with plain nitrogen and a third with chicken manure. “That was my grandmother’s theory,” he said. “If you have any problem, just add some manure.”

Within two or three days, the straw heated up to 130 degrees as it began to break down. After about a dozen days, the temperature inside the bales cooled to 100 degrees and flecks of dark black dirt began to form in the core. At this point, Mr. Karsten plugged in some tomato seedlings.

What the trial lacked in scientific rigor, it made up for with results. “What I discovered after the first year is it didn’t really matter what I put on the bales: it all worked,” he said.

Still, Mr. Karsten did not take success as proof of his genius. “I always say to myself, I know I couldn’t be the first person to do this,” he said.

In a phone call a few weeks ago, Linda Chalker-Scott, an urban horticulturist, confirmed Mr. Karsten’s hunch. “There are a ton of articles out there — dozens, if not hundreds,” she said. From the 1950s through the 1980s, commercial growers experimented with straw bale, arranging it in greenhouses or laying it in outdoor trenches.

The technique proved useful in the Middle East, where alkaline and saline soils resist cultivation. Straw bale was apparently common in Eastern Europe too (although sampling the literature requires a working knowledge of Armenian or Ukrainian). Eventually, she said, lightweight growing media like perlite replaced straw: “I think this stuff was all but forgotten on the scientific level.”

Dr. Chalker-Scott, 55, often debunks quack gardening advice on a blog called “The Garden Professors,” co-hosted by her extension service at Washington State University. A few weeks ago, for instance, she disputed the virtues of spraying molasses on your plants. (Seedlings also don’t like fro-yo or peanut butter and jelly.) “It seems like we’re always looking for the newest and shiniest way of producing vegetables,” she said.

Yet she liked straw-bale gardening as a low-cost technique that uses natural waste materials and mimics natural processes. “This is one of those practices,” Dr. Chalker-Scott said, “that disappeared for no good reason.”

A DOZEN YEARS AGO, Amelia Carkuff moved her home and interior design business into a 16,000-square-foot mattress warehouse in downtown Memphis, Tenn. The yard offered two growing environments. “I have essentially asphalt streets on two sides, and the third side is all concrete,” she said. “I had thought for years, ‘How can I bust through this concrete to get down to the earth?’ ”

Ms. Carkuff, 44, drew on the farming wisdom of the ancestors. “I went and found Joel Karsten’s Facebook page,” she said, “and decided, I’m going to try this.”

She deposited the bales outside the front door. “I knew if the bed was not in visual proximity to my coming and going in the building, I would not take care of it,” she said. But given the high-visibility spot, “I did not want it to look shabby.”

Ms. Carkuff’s design solution? “The top half of a twin-sized children’s bunk bed perfectly fits five bales of hay,” she said. “I found it on the side of the road. How sophisticated that sounds, I don’t know.”

She filled the straw corral with tomatoes, peppers and cucumbers. Herbs like basil and oregano grew from the sides of the bale. In recent years, she has added a trellis and planted vines to screen off the air-conditioning units on the south side of the old brick warehouse. She now cultivates some 24 feet of bales, which she picks up for $4 apiece at a local horse-and-feed store.

Her greatest bounty, she said, has been butternut squash. A few years back, Ms. Carkuff cooked the harvest into a hogshead of soup and canned it for a few dozen friends and clients at Christmastime. “It was very Martha Stewart compared to my usual urban persona,” she said.

Ms. Carkuff has disseminated straw bales to some of her friends in the suburbs. The ordinary course, Mr. Karsten explained, “is you become a teacher, then a preacher.”

For example, he receives occasional correspondence from one grower, Lorna Donaldson, who will be teaching straw-bale workshops this week in New York. (Sunday’s class starts at 1:30 p.m. at the Brooklyn Fireproof Café East in East Williamsburg and is $35; Ms. Donaldson also plans to lead classes in early May. Information: strawbalesplus.com/workshops.html.) “She’s become a huge fanatic,” Mr. Karsten said. “As much as I love it, she loves it as much or more.”

Ms. Donaldson, 60, recalls her father growing vegetables in straw some three decades ago. And in the ’90s she planted as many as 2,000 bales for her own organic truck farm in Tiptonville, Tenn. More recently, straw bale has become something of a mission. Last winter, she moved into a transitional housing shelter in Mobile, Ala., and helped the women and children there start a 250-bale garden.

“Most of the people we are working with now don’t have the capital to buy a lot of tools,” she said. And straw can be managed with little more than scissors.

Ms. Donaldson also advocates straw bale as a kind of green laboratory for small-scale entrepreneurs in Gulf Coast towns like Biloxi and New Orleans. “Most coastal communities all over the world have the same problem,” she said. “Usually the soil is depleted, compacted and contaminated by storms.”

She could just as well be describing parts of Brooklyn or, say, Kearny, N.J., just north of Newark. That’s where Jenny Mach, a 32-year-old middle-school science teacher, has been organizing a new community garden.

The site will be in the flood plain of the Passaic River, “one of the most polluted rivers in the country,” Ms. Mach said. “We have signs in our town that say the crabs are cancerous. Don’t eat them. We’re weirded out by the soil there.”

She added: “Even if there wasn’t pollution there, people in the community might be reluctant to plant right in the ground.”

The usual alternative would be to use raised containers filled with potting soil. “But first, we don’t really feel like building them,” Ms. Mach said. “And they’re hard to move around. Once you’ve built them, you’re stuck with that configuration.”

With straw bale, you have a planting space one year and dirt the next. That prospect is appealing to Ms. Mach, as she hopes to start the garden with 8 or 10 friends and volunteers. It was her husband who ambushed the mayor at a yard sale and proposed the community garden. And a few months later they were meeting with the city council.

If the garden works, they’ll offer slots to the public next spring. Straw bale, she said, is almost an attraction unto itself. “I believe it will start a lot of conversations in the community.” Which is a good way for Ms. Mach to meet the immigrants who make up the new heart of Kearny.

“In our neighborhood,” she said, “I’m pretty sure that my husband and I are the only people who don’t speak Portuguese or Spanish. I’m not kidding.”

And maybe that’s the spirit of straw bale. When the villagers come bearing pitchforks, they must be sowing a garden.

If You Don’t Live Near a Farm...

DON’T BUY HAY. When you’re sourcing your first straw-bale garden, start there. Straw, be it oat straw or wheat straw, is the hollow plant tube left behind after you harvest the seeds. Hay is a grass or alfalfa with the seed head still attached and waiting to sprout.

If you live someplace in America where a night of drinking can end in joy riding on the tractor, you have probably crashed into a straw bale down the road. For everyone else, there’s Lowe’s and the Home Depot, or the local garden center. These stores are likely to stock bales around Halloween, Joel Karsten explains in “Straw Bale Gardens.”

“Get it in the fall,” he said, “and throw it right out in your garden.”

Have the big-box bales been sprayed with pesticides or herbicides? The vendors at your local farmers’ market are more likely to know the provenance of their straw. Mr. Karsten has established a straw exchange on his Web site, strawbalegardens.com. A woollier marketplace is Craigslist, which is great if you’re hoping to barter a vintage yogurt maker for a bale.

The Urban Garden Center on Park Avenue in East Harlem charges $12 for a bale, with a $25 delivery fee to the street. Dimitri Gatanas, whose family owns the store, reported that last fall, “we sold more than we have in 50 years.” When straw is a hot commodity in Manhattan, something strange is blossoming.

Another city option is CG Feeds (that is, Crazy Goat Feeds) in Rossville on Staten Island.

Straw is cheaper and more plentiful as you head up the Hudson River to those towns with the funny Dutch names. Like Kerhonkson, west of New Paltz, where you’ll find Kelder’s Farm. A bale here costs $8, and there’s plenty to go around.

But enough about straw. Here’s what else you’ll need: a soaker hose (perhaps on a daily timer) to keep the bale wet, a permeable landscape fabric or heavy mulch to keep weeds from growing between the bales and a bag of sterile potting soil to start seeds or heel in your transplants. Most important is the fertilizer. What kind to use? Well, what kind of gardener are you?

“For the organic folks,” Mr. Karsten said, blood meal and feather meal will take care of the nitrogen. (Bone meal and wood ash from the fireplace can fill in phosphorous and potassium.) You’ll want three pounds of the organic stuff for each bale, applied over the course of a week. Water the top (that’s the bristly, cut face, without the twine). And don’t overdo it, otherwise you’re washing the fertilizer onto the lawn or into the sewers.

Mr. Karsten often uses lawn fertilizer with more than 20 percent nitrogen (and no added herbicides). About 2 1/2 cups per bale will do the job.

After a few days, the straw will go from absorbing nitrogen to releasing it. When the inside feels just a little warm to the touch, you can transplant your seedlings. At this point, you’re done feeding the bale. Now it’s time for the bale to feed you.