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Impacts to sagebrush habitat are threatening the survival of hundreds of sagebrush obligate and associated species and decreasing rangeland ecosystem goods and services. Wyoming big sagebrush (Artemisia tridentata Nutt. ssp. wyomingensis) is a dominant shrub on the more arid portions of the sagebrush biome. Efforts to reestablish this species through seeding has been met with limited success. In general, germination timing can have a strong influence on the ability of a plant to establish. Altering the timing of germination for Wyoming big sagebrush may improve the establishment of this species. Seed germination timing can be adjusted by altering the planting date. Seed enhancement technologies also offer a novel approach to controlling germination timing. The plant hormone abscisic acid (ABA) can be applied to seeds to delay germination. Conversely, the plant hormone gibberellic acid (GA) can be used to accelerate germination. The objective of our research was to understand how planting date and application of ABA and GA treatments influence germination timing of Wyoming big sagebrush. Seed was either left untreated, treated separately with 5 concentrations of ABA and treated with 5 concentrations of GA. Hydrothermal germination models were developed for each seed treatment and applied to field soil moisture and temperature data to predict germination timing. Simulated planting dates were tested at monthly intervals from October � April on 8 different years at 6 different Wyoming big sagebrush sites. Results indicate that planting date, ABA, and GA concentrations can have a strong influence on seed germination timing. Depending on the planting date, and coating application rate, simulations show that ABA or GA could alter germination timing to occur in windows that appear to have more favorable temperature and moisture conditions for plant establishment.