The keynote speaker at the recent Garden Day seminars in Fergus Falls was fascinating. Joel Karsten described his development of straw bale gardening, which seemed to me the ultimate in raised gardening. Joel was raised on a tree nursery and crop farm in southwestern Minnesota where he learned much from his grandmother and father. He graduated from the University of Minnesota in Horticulture Science and he is a member of the Certified Nursery Professionals. In addition to lecturing on the subject, he has written 'A Guide to Growing a Straw Bale Garden', which is available on his website, strawbalegardens.com or on Amazon.
Straw bale gardening is a different type of container gardening, in which the container is a straw bale held together with two or three strings. Once the straw inside begins to decay it becomes 'conditioned' compost and is a great plant rooting environment. One must begin the process of conditioning by the first of May.
There are many reasons to try straw bale gardening. The bales can be placed in any area that is convenient and sunny, including a cement driveway as I intend to do. The bales require minimum attention and have maximum production. Gardeners who are unable to do the heavy work of gardening like lifting, tilling, constant weeding and fighting insects will appreciate this method. The bales are at a nice height to work on for those who find it difficult to bend over or are in a wheelchair. Poor soil, limited space, low cost, flexibility in placement and great performance all are good reasons to give this a try.
Straw is the stalk portion of small grain crops such as wheat, oats and barley and is not to be confused with the grass based bales of hay that take much longer to decay. Straw holds moisture very well and drains well. It is weed free, easy to find and inexpensive. It doesn't matter how old the bale is as long as the strings are strong. Place them in any area that gets 8 hours or more of sun a day and is convenient to a water source.
The bales must be placed with the strings on the sides and the cut ends of the straw facing up. Put landscape fabric or old carpeting underneath the bales. Arrange no more than five bales end to end with a 6 to 7 foot post or stake at each end. Leave enough space between the rows to be able to mow if you place them on grass. String 14 to 16 gauge wires between the stakes to support climbers. Make the bottom wires double at 10 to 12 inches above the bale and the others ten inches apart. The double wires make it easy to hold in plastic or a spun fabric like Reemay to protect from early cold spells.
The process of conditioning the bale takes ten to twelve days depending on the outside temperature. On day one, evenly sprinkle ½ cup per bale of any high nitrogen fertilizer, such as a lawn fertilizer without herbicide. Spray the bale with water to wash in the fertilizer. On day two water the bale, day three add ½ cup fertilizer and water, day four water, day five ½ cup fertilizer and water, day six water. On days 7 through 9 spread ¼ cup high nitrogen fertilizer and water. On day 10 spread one cup of 10-10-10 fertilizer and water it in. Decomposition inside the bale will occur and it will become very hot. It will result in a lovely nitrogen rich media where worms and mushrooms may occur (good things).
On day 11 or 12 open a crack in the bale with a trowel to insert started plugs, seal up the crack with potting mix and water. You can direct seed by adding two inches of potting soil or compost on top of the bale. Protect the seedbed with seed tray covers or tent them with plastic threading it through the double wires and the bottom bale string. Flowers can be inserted into the front of the bale to make it more attractive.
As the bale continues to decay it will produce heat from the bottom for 6 to 8 weeks. This will promote good seed germination and rapid root growth. The heat will offset cool nights while the cool tops help prevent disease growth.
Vegetables except for corn (it falls over), root-crops, vines, herbs, and flowers are all possible with this method. Rhubarb, asparagus, strawberries and perennials are not advised because at the end of the season the bale falls apart.