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Historically, calendar date has been used to determine when cuttings are collected for rooting. However, year-to-year variations in climate limits the usefulness of using calendar date. More recently, rooting of stem cuttings has been associated with chilling accumulation. In the winter, daily temperatures in northern New Mexico can fluctuate from below freezing to well above freezing. Eight chilling accumulation models and calendar date were tested to determine the best predictor of rooting of white fir. The chilling accumulation models ranged from those based on number of hours at low temperatures to weighted models that calculated chilling unit accumulation and loss. In addition, temperature data based on 3-, 6-, 12-, and 24-hour averages were used. Most of the models were better than calendar date in predicting rooting. The best model was a weighted model that accumulated chilling from -5 to 10C with loss of chilling >15C and less than -10C. Other models that performed well included models that accumulated chilling from 0 to 7.2C, 0 to 15C, or -3.5 to 10C. On the average, the data based on 12-hour means was the best for modeling chilling accumulation to predict rooting.