The sap runs intermittently over the next 4-6 weeks or until the weather warms up and buds begin to form on the trees. This usually occurs around early to mid-April. The maple trees that produce this sap are at least 40 years old, and it takes 40 gallons of sap to produce just one gallon of syrup. That means it takes the annual sap output of four mature maple trees to make just one gallon of maple syrup! To this very day, Vermont remains the largest single producer of maple syrup in the United States.