Hardwood and some softwood bark composts release high amounts of manganese. High manganese must be corrected through addition of iron sulfate to the mix or toxicity will develop on manganese-sensitive plants. All of these properties must be taken into consideration during mix formulation. One factor largely taken for granted by the nursery industry is the potential for natural disease suppression supported by compost-amended mixes. Although fungicides are available that control root rots, drenching over a two-year period far exceeds the cost of natural suppression.
Most growers treat crops such as plants in the Ericaceae three to four times per year.
This is a significant total cost. Thus, disease suppressive properties are very important. This article reviews properties of materials for use in container media readily available in Ohio. A short section on mix preparation is included. Sphagnum Peats Nurserymen typically use reed-sedge or sphagnum peat.