by Sharon Morrisey, Horticulture Agent for Milwaukee County and advisor to UW-Extension Master Gardeners
For a new twist on container gardening, try straw bale gardening. This emerging technique skips the container and substitutes partially decomposed straw for potting mix.
It starts 11 days before planting after the bales are put in place. Lay them so the string is on the sides and not the bottom. A stake driven in at each end will help hold bales together. Tall stakes can double as end posts for vertical supports to hold vines or tomato plants.
Conditioning the bales begins with three days of thorough soaking. For each of the next three days, sprinkle 1 cup of ammonium sulfate or 1/2 cup of urea on top and water soak again.
For the next three days, use one-half as much fertilizer. On day 10, simply water. If, on day 11, the bales no longer feel warm on top, you can plant. Otherwise, wait until they cool to body temperature.
Transplanting into the bales only requires stabbing into the straw and prying open a space large enough for the roots. To sow seeds for individual plants, pack a little potting mixture into the openings you make, place the seed at the proper depth, cover and add a little mulch to hold moisture and prevent the potting mix from washing away. To make rows for crops, such as lettuce or spinach, use your trowel to cut a trench, fill with soil, and plant.
The rest is the same as traditional container gardening. Water daily and do not allow bales to dry out. A soaker hose running the length of each bale will make this much easier. Fertilize once a week with a water-soluble, balanced fertilizer.