Richard grows three acres of nursery crops in containers. He was interested in comparing slow-release organic fertilizers with a conventional controlled release fertilizer. His hope was that by using organic fertilizers he could reduce the loss of nutrients through run-off, mitigate salt build-up, and provide a more constant rate of release of nutrients to his crop.
Richard placed several hundred ornamental plants—junipers, spirea, dwarf burning bush, and gold thread cypress—in one- or two-gallon nursery containers with a growth medium consisting of composted landscaping waste, used mushroom compost, peat, and red shale. The pH of this medium varied between 6.5 and 6.8. Organic fertilizers manufactured by the Fertrell Company of Bainbridge, PA were applied to some pots. These were in 4-6-4 or 3-3-3 concentrations. A conventional controlled-release fertilizer (Osmacote, 14-14-14) was applied to other pots for comparison. All fertilizers were top-dressed, according to manufacturers’ instructions. Control plants were grown in the same mixed growth medium, but received no applications of any slow-release fertilizers. All plants were watered with a solution containing 2 tablespoons of ground kelp and fish per gallon.
Results: Richard and several of his collaborators gave the plants a subjective evaluation. In the case of spirea, the plants receiving fertilizer, whether Osmacote or organic, appeared slightly bushier and larger than the controls. Otherwise controls and treatments were indistinguishable for color, size, or bushiness. Richard notes that these ornamental species require two years to reach marketable size, and that growth in the second year is more dramatic than that in the first. This project continues through a second year as FNE00-320.