Poor soil? No land? Try growing in straw. That’s the advice from a farm-bred gardener who has published a book to share his methods.
This year’s growing season is not exactly off to an early start.
But a local gardener has a suggestion: Plant your vegetables in a bale of straw instead of in the ground.
It’s a humble method with old, rural roots, one that Joel Karsten of Roseville has been advocating for more than a decade. He started experimenting with growing vegetables in decomposing straw, inspired by his childhood memories of tall, healthy thistles sprouting out of wet bales on the farm. Encouraged by his results, he started teaching community education classes throughout Minnesota and Wisconsin, picking up almost 25,000 Facebook “likes” along the way. Now he’s published a book, “Straw Bale Gardens” (Cool Springs Press, $19.99), which was featured last month in the New York Times.
What’s so great about growing produce in old, rotting straw bales? Earlier vegetables, for one thing, according to Karsten. That’s enticing to cold-climate veggie gardeners, especially this year, when gardens remained buried under snow more than a month after the official start of spring.
So how exactly does straw-bale gardening deliver early vegetables?
“When you put tomatoes in cold soil, they just sit there until the soil gets to the right temperature,” Karsten said. But with a bale, “you create a really nice growing environment, similar to an expensive greenhouse.” Once you “condition” your straw (which means starting the process of decomposition), the interior of the bale heats up. By late May, its temperature could be 85 to 90 degrees, vs. 55 degrees for soil in the ground, he said, leading to rapid root production.
Tomatoes and cucumbers, in particular, prefer warm roots and cool tops, according to Karsten, but it’s very difficult to get that combination in the ground. In fact, planting veggies in a warm bale, rather than the chilly ground, reduces days to maturity by 10 percent, he said.
Karsten has tested it many times, he said. “It’s really fun to do a comparison, put a pepper plant in a straw bale and one in the soil,” he said. “A month later, the one in the bale is 20 inches taller than the one in the ground.”
John Ullmann of St. Louis Park is a bale believer. He took one of Karsten’s classes several years ago, and has grown veggies in bales the past two growing seasons, with plans to do it again this year.
“This is really my only way to have a vegetable plot,” said Ullman, who lives on a heavily shaded lot on Minnehaha Creek. He sets his 10 bales right in his driveway, the sunniest spot on his property. “You can put the bales anywhere, right on the asphalt.”
Gardening without a garden
That’s another benefit of straw-bale gardening, according to Karsten: You don’t have to have good soil — or even soil at all — because you’re basically creating your own, inside the bale as it breaks down. But you do have to give the bale a little help.
“People e-mail me saying they tried it and it didn’t work, the tomatoes died,” Karsten said. “I ask what they used as a conditioning process, and they say, ‘What is conditioning?’ If you don’t condition, you’re guaranteed to fail.”
Conditioning isn’t complicated, he said. “You’re basically adding fertilizer and water, for 12 days, to get the bale ready to go.”
Another mistake to avoid: Don’t use hay for your straw-bale garden. (Yes, city slickers, there is a difference.)
Hay and straw are often confused by those who didn’t grow up on a farm, but they refer to different plants entirely. Hay is usually baled grass or alfalfa, green in color, and used as food for livestock. Straw is yellow or golden, a byproduct of what’s left after small-grain crops are harvested and cut near the ground, with seeds separated from the stems. Straw has little nutritional value, but makes a good bedding material for livestock.
Because hay, unlike straw, contains seed heads, it’s not recommended for straw-bale gardening, because the hay seeds will compete with your crops.
If you don’t have access to a farm with straw, you can find bales for sale at www.strawbalemarket.com, a website Karsten started to help gardeners and farmers connect.