beverages from their mineral - rich sap right now is the time mid - april when temperatures during the day warm to the 40 s - 50 s and the nights dip below freezing it’s the fluctuation of temperatures that affects the flow of the sap rising temperatures produce pressure within the tree causing sap to flow at night when the temperatures fall below freezing the tree pulls water up through the roots replenishing the sap this cycle continues until the trees start to sprout buds