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Seed germination and seedling vigor of Wyoming big sagebrush (Artemesia tridentata Nutt. ssp. wyomingensis) were evaluated following manipulation of seed moisture, a practice benefitting many species. At the time of harvest, seed moisture ranged from 2.3 to 9.0% for 5 collections tested and seeds with moisture between 5 to 6% had the highest and most rapid germination. Seed moisture changed during storage, but germination percentage was not affected by post-harvest seed moisture change, indicating that germination is related more to habitat or genetic variations than the initial moisture content. Seedling vigor increased after storage, suggesting that after-ripening may be required. Seeds of 2 commercial collections were subsequently humidified at 2, 5, 10, and 15 degrees C for up to 15 days, or to 60% moisture content. Seed moisture increased most gradually at 2 degrees C and seeds held at 10 degrees C attained a higher moisture level than at other temperatures. Germination percentage, germination rate, and seedling vigor were similar between treatments and controls regardless of seed moisture change. Imbibition temperature did not affect germination percentage or seedling vigor, but the time to 50% germination decreased with increasing imbibition temperature. We conclude that artificial seed moisture management did not affect germination percentage, germination rate, or seedling vigor of this species when tested under optimum moisture conditions. Germination is more related to habitat or genetic variables than initial seed moisture content.