Enough chilling hours are required during the dormant season to satisfy the plants need for dormancy. Insufficient chilling hours may delay bloom or even the breaking of dormancy and growth of the tree in the spring. Chilling hours are typically calculated at an optimum temper-ature of 40 degrees F. Over 50 degrees F no chilling hours are accumulated. Under 32 degrees F no chilling hours are accumulated because the plant is fully dormant with no cellular activity. The total numer of hours during the winter that the plant is in that 32-50 degree range will