Birch sap is usually collected at the end of winter and the beginning of spring when the sap is moving up the tree. A bottle is tied to the tree and a hole is drilled into its trunk. A plastic tube leads the sap that drips out to the bottle.

Each mature tree will produce about a gallon of birch sap each day for 10 to 20 dasy during a season that only lasts about a month. Birch sap must be collected before any green leaves have appeared in the spring, otherwise it becomes bitter.