Water Activity

Water activity (aw) measures the availability of water molecules in cannabis material, expressed on a scale from 0.0 to 1.0. This metric is critical for preservation rather than aroma generation itself, but it directly governs which volatile compounds remain stable and which degrade or volatilize during storage. Cannabis maintained at aw levels between 0.55–0.65 typically retains terpene profiles more consistently than material stored at higher moisture levels, where microbial activity and enzymatic breakdown accelerate. Lower water activity (below 0.50) can cause brittleness and volatilization of lighter terpenes. Breeders and seed banks monitor water activity to ensure genetic material, seeds, and archived clones preserve their chemical signatures accurately across years.

Seed bank curators and breeders use water activity monitoring to maintain seed viability and genetic fidelity during long-term storage. Preservation protocols targeting specific aw ranges help ensure that stored genetics express their intended aroma and terpene profiles when grown, rather than degraded or altered phenotypes.