Did the thought of the work involved in starting a vegetable garden keep you from having one this year? Did time for all that rototilling or digging in of compost never materialized? Or maybe you tried a garden in our clay soils and results were poor?
Susan Carlson, a Laramie County Master Gardener, can recommend a solution: straw bale gardening. Her stepson, who lives in Minnesota, brought her the book by Minnesota native Joel Karsten describing his miraculous method.
This is the second season Carlson has used rectangular straw bales for vegetables and her results look good. She also included flowers.
The idea is that a straw bale is compost waiting to happen. Before the growing season begins, over a couple weeks, you add water and a little fertilizer (organic or inorganic) and it will activate an army of bacteria. The bacteria break down the straw, turning it into just what plants need. Plants can be inserted into the bale or seeds can be started in a little potting soil placed on top.
The bale is like a container or raised bed held together with baling twine. You can set it anywhere, even on a driveway. You don’t have to prepare the ground underneath.
And, depending on how clean the straw is, you will have few weeds, or wheat or oat sprouts, that can’t be easily removed by hand. You’ll have more sprouts if you accidently bought hay—which includes the heads of grain—instead of straw, which is just the stems.
Straw bales might also be the solution to vegetable plant diseases that persist in soil. Gardeners are always advised not to grow the same family of vegetables (especially the tomato-eggplant-pepper family) in the same spot more than once every three years. You can start a fresh bale each year, although Carlson managed to keep her bales intact for a second year.
Carlson studied Karsten’s book, “Straw Bale Gardens.” Here’s what she did:
First, obviously, she found straw bales.
I checked a local farm and ranch supply store and their regular bale, about 3 feet long and 60 pounds, runs about $7. Avoid the super-compressed bales.
A bale bought in the fall from a farmer should be cheaper than in the spring, after they’ve had to store them all winter. In fall, you can put your bale outside to weather.
If you’ve had problems with mice or voles, as Carlson has, lay chicken wire or hardware cloth down first. Cut a piece big enough to fold up and protect several inches of the sides of the bale.
Lay out your bale prickliest side up, and so the sides wrapped with twine not against the ground. Carlson bought five bales and formed them into a u-shape to fit within an area fenced to keep out her dogs.
Because she planned to grow beans, Carlson made a trellis as well. She wedged two bales, lying end to end, between two 5-foot steel “T-post” fence posts (about $5 each) and then strung wire at about 10 and 20 inches above the bales. She can add more wire if the plants get taller. Karsten recommends 14-gauge electric fence wire (but you won’t be plugging it in).
On the ground inside the u-shape of bales (or between your rows), Carlson laid landscape fabric. You could use some other material to keep light from germinating weed seeds, like a layer of thick straw, cardboard, wood, wood mulch, etc.
Next, Carlson “conditioned” the bales starting about two weeks before our last frost date, which is around May 22, though you can start a week earlier because the bales form a warm environment.
The first step here is to find cheap lawn fertilizer with at least 20 percent nitrogen content. Do not use one that is slow-release or that contains herbicides.
You can also use organic fertilizers, like bone or feather meal, or well-composted manure, but you need to use six times more than the amounts given for inorganic fertilizer. The second season Carlson said she is having good results using Happy Frog packaged organic fertilizer, but using much less since the bales were conditioned once already last year.
The conditioning regimen begins the first day with a half cup of inorganic fertilizer (or six times more organic) per bale sprinkled evenly all over the top and then watered in with your hose sprayer until all of it has moved into the bale and the bale is waterlogged, writes Karsten.
The next day you skip the fertilizer and water the bale again. Karsten suggests using water that’s been sitting out for a while so it isn’t as cold as it is straight out of the tap.
Days three through six you alternate between fertilizer-and-water days and water-only days.
Days seven through nine you water in a quarter cup of fertilizer per bale each day. The bales should be cooking by now and feel a little warmer on the outside.
On day 10, add a cup of 10-10-10 garden fertilizer. The numbers mean 10 percent nitrogen, 10 percent phosphorus and 10 percent potassium.
Next, lay out your soaker hoses on top of the bales if you are going to use drip irrigation as Carlson has.
On day 12, Carlson transplanted one cherry tomato plant directly into the bale, wedging it in. Smaller plants are easier to plant than large ones and will soon catch up.
“Bacteria are breaking down the inside of the bale and making this nice environment,” said Carlson.
Carlson wanted a salad garden and so she started everything else from seed: edible pod peas, Haricot vert beans (a type of tiny French green bean), lemon cucumbers, broccoli, spinach and various lettuces.
She packed a couple of inches of sterile potting soil (not garden soil) into the tops of the bales in which to plant the seeds. The warmth of the composting straw got them off to a good start. She added shade cloth overhead to protect the lettuces from too much sun and started cutting romaine and butterhead lettuce by mid-June.
Carlson also used shade cloth on the west side of her fence to keep the wind from drying out the bales too quickly.
And there you have it, a vegetable garden—or a flower garden if you prefer—ready to grow. All you need to do then is to garden as you normally would: enough water, fertilizer once a month, and pull the occasional weed that may sprout, or pick off any little slugs or insects.
Maybe because of our dry western climate, Carlson was able to use her bales this second year. The bales shrank a little so she patched the gaps between bales with bits of chicken wire on the sides and filled them with potting soil.
One question is what to do with the old bales. They are great compost for conventional garden beds. Carlson reached into the side of one bale and showed me lovely black soil. If you don’t have any conventional garden beds to add it to, someone else would be happy to take the compost off your hands.
“This isn’t the prettiest thing,” Carlson says of her straw bale garden, “but when it starts growing, you don’t even look at the bales.”