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.