Apple trees begin visible growth in the Spring of the year after having had their chilling requirement met, measured as chilling hours (800-1200 hours), followed by a specific amount of warm weather, measured as growing degree-hours (approx.. 300 hours). The first growth to appear in the Spring is the leaves and the trees will bloom approximately 3-4 weeks later. The date on which apple trees bloom in a location can vary annually based upon fluctuating winter and spring temperatures and …