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Karsten enthusiastic about gardening technique

ROSEVILLE — Gardeners often spread straw as mulch on their garden beds, using it to retain moisture and control weeds.

But a whole bale of straw can actually become a vessel for planting vegetables and flowers, offering the same advantages — plus many more.

Worthington native Joel Karsten has become an expert in the straw bale planting method, having developed the process through his own experimentation. He’s written a booklet detailing the method, teaches community education classes on it, hosts a website and Facebook forum and is a frequent speaker to garden clubs and other community groups.

Karsten, son of Glenn and the late Barb Karsten, grew up on a farm outside of Worthington, where his dad runs a tree nursery. A 1987 graduate of Worthington High School, he earned a degree in horticulture through the University of Minnesota and worked in landscaping for a few years before pursuing other interests. But gardening has always been near and dear to his heart, and he is now passionate about the straw bale method.

“About eight years ago I sort of stumbled across the concept,” said Karsten, who now lives in Roseville and runs a toy and novelty manufacturing business there. “It was early morning and I was listening to a radio show and heard a conversation between a gardener and gardening show host. He was asking if he’d ever heard of growing a potato under a slice of straw and how it worked, how the straw would help to keep the weeds down. I started thinking: I wonder if you could grow other things in straw?

“So I talked to my dad and asked him if he thought you could try rotting a straw bale and turning it into a container so that the straw bale is the container and also the media,” Karsten continued. “He said, ‘Let’s start trying.’ So we tried some different recipes for decomposing inside the bale, and it worked very well for all the different crops we planted. So we kept doing it, and people would stop over at my dad’s and ask, ‘What are all these bales?’ So he finally asked me, ‘Could you write something down to give to people so I don’t have to explain it every time?’ That was the impetus to create a syllabus for a book, which eventually became a full-blown book.”

The advantages of straw bale gardening are many, according to Karsten.

“Some are very obvious,” he said. “The most obvious is that it’s up off the ground, so it’s perfect for people who are older or disabled, who can’t get down on their knees, because it’s 20 to 22 inches above the ground.

“Secondly, your soil is filled with weed seeds, and because this is freshly decomposed straw and you’re depending on the straw itself to grow in, you’ll have very few weeds. I tell people you give yourself 30 seconds per bale per summer, and that will take care of your weeding needs. Only what you plant is going to sprout for the most part.”

Straw’s ability to retain moisture also helps with watering the plants.

“It tends to hold moisture really well,” Karsten explained. “They use it for animal bedding because it’s really absorbent. The hollow straws will absorb water into them, so it has a high water-holding capacity.”

Gardeners will discover other advantages as they go through the process, Karsten noted. For instance, the bales can act as independent greenhouses in the spring.

“As the straw decomposes early in the spring, it starts to produce heat, kind of like a compost pile decomposes,” he detailed. “As it starts to heat up, probably 10 to 14 days into the process, you’re going to put plants into the bale. Early in the season, you can cover the bale with poly, pull it around one side and tuck it into the strings, maybe use a support across the middle to hold the plastic up, and it creates a little greenhouse. As it heats and decomposes, you get really rapid root production, and top growth on the plant, also.

“When you pull the poly off, you’re usually a month ahead in the gardening process,” Karsten continued. “It’s great for short-season crops, like tomatoes. You’ll have the first tomatoes on the block if you use this process, because they mature much quicker. On Mother’s Day, or around May 15, the soil temperature is usually 55 degrees for most people. That’s when the lilacs are in full bloom and vegetable seeds will begin to germinate. If you can have plants at the three- or five-leaf stage by May 15, we’re going to get mature crops much more quickly in the fall.”

Through his website and Facebook page (found under the name Learn to Grow a Straw Bale Garden), Karsten has heard from devotees who do it on a large enough scale to sell at farmers markets and people as far away as the Arctic Circle and the southern hemisphere who have succeeded with his techniques.

“They might not be using oat straw, but other organic plant parts, stems of plants, any organic plant part that’s tightly baled will work,” he said. “In some places they use sugar cane stalks or palm fronds. You just need to leave it in the bale form. It’s the tight compression of the bales that cause the rapid decomposition.

“The big advantage we have here is that oat straw is cheap, readily available and tends to work better because of the hollow stem structure. You can do a straw bale for $3, and it’s both the media and the container. If you built a wooden container and filled that with some real nice potting mix bought by the bag, it would probably cost $100 to build the container and another $100 to fill that container. Here, you essentially have the same thing, and it’s pretty amazing what you can produce out of a three-bale garden. You can plant the top of the bale and also plant the sides of the bale. If you want, you can put flowers in the sides of the bale and make it look pretty, or herbs. You can fill the whole bale so it looks like a Chia pet.”

Straw bale gardening can be done with just a few bales or a whole garden full. Last year, he scaled down his own operation to just fewer than 200 bales, he noted, and this year expects to plant about 150.

“We do five bales in a segment, so every five bales are segmented apart with a post on each end and wire between each post to create a trellis of wire above the bale,” he said. “That gives support to whatever’s growing and also holds the poly across the bale.”

The key to straw bale gardening, Karsten shared, is the preparation of the bales before planting.

“You have to do conditioning of the bale,” he stressed. “If you don’t condition the bales — that recipe that we give them for adding nitrogen and moisture and giving it time — if you don’t let that happen first, your plants aren’t going to be successful. By adding a source of nitrogen to that straw, we’re feeding the bacteria inside the bale that are already there. When you add nitrogen and moisture, that’s what the bacteria need to replicate, and they grow like crazy and start to eat the straw. When the bacteria consume enough of the straw, now they stop using nitrogen and start giving nitrogen back to their environment.”

Karsten hears the best success stories from people who properly condition the bales; the ones who report problems generally haven’t done the process properly or plant too early.

“Tomatoes do really well,” he said. “Potatoes do remarkably well. I hate to single plants out, because most of them work with this, although some just don’t make sense, like sweet corn, which is too big and floppy. Your strawberries, rhubarb, asparagus need to be in soil because it takes several years for them to get established, so they don’t adapt well to it. But almost anything else does well. People ask me about something like carrots: Do they look the same, taste the same? They are much better — nice and straight because the root, which is what we’re eating, has less resistance as it grows, so it tends to get really long and skinny, which is desirable. You can multitask a bale as well, do the old-fashioned square-foot gardening and overlap crops with the same type of technique. Like with a tomato plant, you can plant other things before a tomato even casts a shadow, like radishes with a tomato.”

Karsten also reported luck with sweet potatoes and garlic, which typically don’t grow well in our northern climate. His advice to anyone who may be skeptical of the process is to give it a try.

“Start with at least a couple or three bales and jump in with both feet,” Karsten suggested. “Don’t be afraid. Use a soaker hose to keep it watered. Amaze yourself and your neighbors. Don’t worry if you get mushrooms — it’s the type of environment that they love. And don’t panic when your neighbors come over and tell you you’re crazy. You’re the one who will be laughing in the fall.”

Karsten’s book, “Guide to Growing a Straw Bale Garden,” is available through his website, www.strawbalegardens.com. It is also available in PDF format.

Readers may reach Daily Globe

features editor Beth Rickers at 376-7327.

Tags: news, karsten, straw, gardening