Highlight: Significant relationships were found between yield and age of bitterbrush. Individual plants that were heavily grazed during the spring and early summer produced more forage than plants that were moderately grazed during late summer and fall. Under the heavy grazing treatment, however, plant longevity was sharply reduced and fewer plants survived until the age of maximum production. As a result, only 88 kg/ha of air-dry forage was produced under heavy early-season grazing compared with 172 kg/ha under moderate late-season grazing.