Gardening in a straw bale

As a little boy growing up on a Minnesota farm, Joel Karsten wondered why the healthiest weeds seemed to be ones growing out of broken down straw bales. Years later, after earning a degree in horticulture, he developed a theory around that mystery that is revolutionizing home and community vegetable gardening.

At the time he was a young college graduate with no money and a new home surrounded by fallow constructions fill. Knowing that tomatoes and peppers require the same nutrients as those thistles growing out of the straw on his farm, he began experimenting.

Rather than buying truckloads of expensive compost, he started growing his garden in straw bales with the idea of capitalizing on the internal composting going on inside a bale of straw. It took 15 years of trial and error, but he finally came up with the perfect system.

After a local TV reporter got wind of his work and did a feature, garden clubs began requesting appearances. That led to a website and eventually a book in 2013, “Straw Bale Gardens.” The new edition, “Straw Bale Gardens Complete,” is a top seller on Amazon and one of the hottest titles in the gardening world.

In Sonoma County, a team of food-growing specialists with the Master Gardeners is experimenting with straw bale gardening.

“I’m really excited about it. It’s a lot of fun and so far, it seems to be really easy to do,” said Jeanette Clough, who has several bales going in her Healdsburg garden. She is particularly interested in vertical gardening and the possibilities of demonstrating how straw bales can save not only water but space, particularly with vines.

The key to growing in straw bales is conditioning the bale for 12 to 18 days with a high-nitrogen fertilizer, which hastens the decomposition of the straw inside the bale. It is this compost that becomes the soil in which you plant your starts. Seeds will require a bed of potting soil to hold moisture atop the bale until they have germinated.

Organic gardeners will need about 3 pounds of Milorganite, blood meal, feather meal or a similar source of fertilizer with at least 5 percent nitrogen for each bale. You will also need a small bag of garden fertilizer that contains phosphorus and potassium such as a common 10-10-10. For an organic option, look for bone meal or fish meal for phosphorus and wood ash or kelp meal for potassium. Mix half the wood ash together with another phosphorus source to get a balanced fertilizer with all the essential nutrients.

Karsten, who lives in a suburb of St. Paul, said he did a lot of research trying to find someone else who had done it. But the only reference he came up with were the Incas, who planted crops in mounds of floating swamp grass.

Straw bale gardening has a number of benefits. Chief among them for California gardeners is straw’s water-efficiency.

“They are these long, narrow, skinny tubes and they hold water inside those tubes. It gives straw an amazing capacity to capture and retain moisture,” Karsten said. That capacity for absorbing moisture is why farmers use it for animal bedding material, he added.

Straw bales also have other advantages. Because you’re making your own soil right in the bale, it is pristine and free of insects, weed seed or fungal diseases that may be in regular soil, Karsten said. You don’t need a garden or soil. A patio or even a driveway will do. And since they’re raised, they are easier on the gardener. Once you’ve harvested your crop, you can break up the bale and compost the straw or use it as mulch. (Make sure your bale is straw and not hay, which will have seed in it).

Straw bales are good for most crops, although he doesn’t recommend perennial vegetables like asparagus and rhubarb or corn, which needs a lot of space. But you can grow most common crops like tomatoes - stick cages right in the bale - basil, beets, peppers, cucumbers, squash and greens. For pole beans or tomatoes, you could also buil+ a trellis out of wood or PVC pipes.

Karsten also likes to use them for growing cut flowers. Some people are slow to cut blooms for fear of diminishing the beauty in their garden beds. But in a bale you can grow flowers strictly for the table.

Tommie Smith, a master gardener who lives in Cloverdale, said this is her third season growing in straw bales. She has everything from onions and chard to garlic, potatoes, radishes and beets. She grows both summer and winter crops in bales and is now up to 30 bales this summer, which she buys for about $9 apiece at a local farm supply.

The cost of the bales is a bit of a downside.

“But I’m not buying mulch,” she said, “because I’m using straw from the year before.”

More information can be found at strawbalegardens.com.

You can reach Staff Writer Meg McConahey at meg.mcconahey@pressdemocrat.com or 521-5204.

TIPS ON STRAW BALE GARDENING

Make sure your bale is straw and not hay.

Bales are especially useful if you have poor or contaminated soil, limited space, only paved surfaces or large surface roots from trees.

Each bale will hold 3-5 gallons of water.

If you place a bale on a wood surface but down a protective surface that allows for air circulation, not plastic, such as stall mats sold at farm supply stores.

Water with soaker hoses or hand water with a wand. Each bale will need 1-2 gallons a day.

Put in area with at least six hours of direct sunlight.

Place bales with the cut-straw side up.