A simplified, highly reproducible procedure is outlined for the extraction and polyacrylamide gel disc electrophoresis of acidic soluble proteins from apple bark and arborvitae foliage. The procedure includes low temperature maceration, short extraction time, and an extraction solution which contains polyol and phenolic complexers, a reducing agent, and a non-ionic surfactant. Electrophoretic patterns, total nitrogen, moisture content, minimum survival temperatures, and environmental and morphological changes were examined during the natural dehardening of apple and the controlled hardening of arborvitae. Qualitative protein changes, as evidenced by the appearance and disappearance of specific bands, occurred at times when changes in hardiness were taking place.