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Straw bale gardening

Published June 2, 2016
Herbs planted in straw bale
Herbs planted in straw bale

URBANA, Ill. – For gardeners with limited mobility, poor soil conditions, or limited space to garden, straw bale gardening may be the way to go, according to University of Illinois Extension educator Elizabeth Wahle.

For straw bale gardening, a few basic materials are required: straw bales, as opposed to hay bales, which tend to sprout grass weeds; newspapers for use as a weed barrier, unless bales are being placed on concrete or asphalt paving; a fertilizer source that contains nitrogen, such as urea, blood meal, or bone meal; a water source; soil or compost, if planting from seed; and a hand trowel to place transplants into the straw bales.

“First, decide on the design and placement of your straw bale garden,” Wahle says. “Bales can be arranged in a straight line, blocks, or in complex labyrinth designs. Keep in mind, though, that once you start watering bales, they can no longer be moved easily due to the added weight of the water.”

Wahle reminds would-be straw bale gardeners to plant taller plants on the north end of the straw bale garden to avoid casting shade on other plants.

“Also,” she says, “consider access. Once plants attain a certain height, stepping over a bale to access an interior bale within the design will become challenging and may result in injury to yourself or plants. Beyond that, the only limitation is your imagination and the amount of space available.”

Before moving the bales into place, several layers of newspaper should be laid on the ground under the bales to prevent growth of grass and other weeds. Bales should be positioned so that the baling twine is parallel to the ground.

Before plants can be inserted into bales, gardeners should be aware that the bales must go through a weeks-long process known as conditioning. Conditioning initiates a natural composting process within the bales. During this time, the temperature within the bales will increase significantly. Bales held over from the year before that are still in good condition will not need to go through this step. However, most bales only last for one growing season.

“To start the conditioning process, water the new bales thoroughly and keep them wet for three days. As the inside of the bales begins to decompose, they will begin to warm up. On days four, five, and six, sprinkle the top of each bale with one cup of ammonium sulfate (21-0-0) or one half cup of urea (46-0-0) to speed up the process even more. Water the fertilizer in each day after each application,” Wahle says.

“On days seven, eight, and nine, cut the amount of fertilizer per bale in half,” she says. “Continue to water in the fertilizer, but take care not to water excessively to avoid runoff and leaching of the nitrogen out of the bale. On day 10, stop adding fertilizer, but keep the bales moist. On day 11 and every day thereafter, start monitoring the temperature of the bale.”

Temperature readings should be made before watering or a false reading could occur. Temperatures can be monitored with a compost thermometer or by feeling the inside of the bales. When the bales feel cooler than body temperature, it is safe to begin planting.

Plants can be transplanted just as they would be in the ground, using the same spacing.

“Using a sharp trowel, dig a pocket in the straw and place the plant inside the pocket, down to the first leaf, and let the straw fill in around it. Though a bit more challenging, transplants can also be planted in the side of the bale, but extra care should be taken not to cut the twine while planting,” Wahle cautions.

If planting seeds, gardeners should place a layer of compost mixed with soil on the top of the bale, just deep enough to hold the seed. Seeds can then be planted directly into the soil and covered with a light dusting of soil or peat moss.

Since the straw bale contains no soil, plants will require more fertilizer than if planted in a garden. Soluble synthetic fertilizer or other liquid-based fertilizers like fish emulsion are the most convenient for maintaining nutritional needs throughout the season.

News Writer:

University of Illinois Extension