EXPANDED SHALE AS A POTTING MEDIUM COMPONENT FOR BEDDING PLANTS
Expanded shale and peat moss were mixed in 5 ratios and evaluated as potting media for Petunia and Impatiens. Two grades of shale (coarse and fine) were used. Bulk density increased linearly with increasing shale whereas total pore space and container capacity increased linearly with increasing peat. Air space of peat-fine shale was consistently lower than that of peat-coarse shale when the peat/shale ratio was the same. Container capacity of peat-fine shale was consistently higher than that of peat-coarse shale when the peat/shale ratio was the same. Growth and quality of both bedding plants increased quadratically with increasing peat in peat-coarse shale and increased linearly with increasing peat in peat-fine shale. Highest growth and quality of both plants were found in peat-coarse shale media with at least 50% peat and in peat-fine shale media with at least 75% peat.