Whether you’re an accomplished green thumb or new to growing your own food, gardeners all over the globe are finding success cultivating crops using straw bales.
Horticulturist Joel Karsten quite literally wrote the book on straw bale gardening. His bestselling step-by-step guide — aptly titled Straw Bale Gardens — has sparked international interest in this relatively new method of gardening, especially useful in urban areas and other places lacking tillable soil.
“Nobody is more surprised than me that this has become what it has become,” says Karsten on becoming the preeminent authority on straw bale gardening.
The Minnesota native grew up pitching hay on his family’s dairy farm and now is invited around the world to share his technique with government agencies, nonprofits and DIY gardening enthusiasts. Since first published in 2013, Straw Bale Gardens has been translated into over a dozen languages and remains one of the top-selling gardening books on Amazon.
Karsten says it’s not simply a matter of taking a straw bale and putting plants in it. “If you do that, you won’t be growing much of anything,” he says.
As detailed in Straw Bale Gardens, it is necessary to condition the bale before planting to activate bacteria that naturally break down the straw into fresh nutrients. “It’s Mother Nature’s basic recycling program that’s happening inside of these bales,” says Karsten.
Watering the straw bale for about a week stimulates the bacteria to begin working. Nitrogen-rich fertilizer then needs to be added over several days to kick the microorganisms into full gear. Another week of watering and you should be able to feel heat coming off your straw bale. That’s how you know it’s time to plant your seedlings. Karsten says after carefully working the plant into the straw, you can add a little top soil to keep it firmly in the bale, but it isn’t necessary.
After interviewing Karsten on Wisconsin Public Radio’s The Larry Meiller Show, host Meiller tried using straw to grow veggies in his own backyard. “I’ve had really good luck with tomatoes, squash and peppers,” says Meiller. “It’s very easy, once you prepare the bales according to [Karsten’s] directions.”
Being able to grow vegetables virtually anywhere is what Karsten sees as the most valuable benefit to straw bale gardening.
“You can have a successful vegetable garden on the roof of a building, in a parking lot, on top of compacted or contaminated soil,” says Karsten. “I’ve even met a guy who had a straw bale garden on his boat in the Gulf of Mexico.”
1. Water the bale
Start conditioning the straw bale roughly 20 days after the last frost. The water stimulates bacteria to start working.
Use a generous amount of fertilizer with at least 5% nitrogen content. Karsten recommends organic blood meal fertilizer, but conventional fertilizers work too.
When you feel heat coming from the bale, it’s time to dig a hole for your seedling.
Carefully work the plant into the straw. The straw will not yet look like soil or compost. You may add some soil to steady the seedling, but it is not required. Continue to water; it’s impossible to over-water.