The objective of this study was to determine the relationships between borehole diameter and efficacious stemming type and length for a range of explosive pressures. A preferred material type and size was obtained after a detailed analysis of the data on minimum stemming lengths for retention acquired for limestone aggregate, crushed gravel aggregate, and Ottawa and river sands. Variables including the size, shape, and cohesive properties between the stemming particles and between stemming material and borehole walls were evaluated along with the strength of the rock. The study suggests that proper selection of stemming rock type and size distribution can reduce necessary stemming length, airblast levels, and ground vibration levels. Consequently, breakage can be improved and reductions realized for airblast, flyrock, and ground vibration.