If you have a limited amount of space for gardening, there are some ingenious approaches that can turn a tiny concrete patio or parking area into a productive food garden. Hay-bale gardening is one of these. Astonishingly easy and inexpensive, the method is particularly well suited to plants with shallow root systems such as strawberries (Fragaria x ananassa). There is no digging or weeding involved, and the bale of hay -- or straw, which also works -- brings the additional benefit of raising the growing surface off the ground, making gardening even easier. While strawberries are perennials that thrive in U.S. Department of Agriculture plant hardiness zones 3 through 10, strawberries are grown as annuals in hay bales.
Set the hay bales on a level surface. Drench them with water, and do this for three consecutive days. Hay bales hold water like a sponge and have to be thoroughly saturated to supply the water needs of your strawberries. Place them so the strings that hold the bales together are on the side, rather than on the top and bottom of each bale.
Spread 2 cups of dolomitic limestone over the surface of the bales on the third day to provide the proper pH balance for growing strawberries in the bales.
Spread 1/2 cup of urea fertilizer over the surface of the bales each day for the next four days, watering after each application. The high nitrogen content of the urea interacts with the carbon compounds in the hay bales to rapidly decompose the straw and transform it into a rich growing medium.
Spread a 1/4 cup of fertilizer on the hay bales each day for another three days, continuing to water. The bales are now ready for planting.
Open a series of holes in the surface of each bale. The holes should be about 4 inches deep, 4 inches wide and spaced 8 inches apart. The straw should have a mushy texture by now and be easy to remove with a trowel.
Fill the holes with potting soil and plant one strawberry in each. Gently loosen the roots when planting to free them from the shape of the pot.
Continue watering the bales every few days or whenever they start to dry out. It's hard to overwater the strawberries because the hay bales have an abundance of air space and perfect drainage.
Mix 2 tablespoons of a high phosphorus fertilizer, such as 16-32-0 or 18-46-0, in a gallon of water and give 1 1/4 cups to each plant every three weeks until the end of the growing season.