Tap maple trees for sap in middle to late winter, or from mid-January to March, when night temperatures are freezing, around 20 to 30 degrees Fahrenheit, and days are sunny and around 40 to 50 degrees Fahrenheit. If farmers tap too early, the holes may reseal themselves, producing no sap.
Farmers tap the trees by boring holes into the tree trunks and inserting spiles that funnel sap into a collecting bucket. They boil the sap and concentrate it to produce maple syrup. The sap-collecting season lasts from four to eight weeks, with peak flow lasting only about three to four weeks. The average tree yields about 9 to 13 gallons per season. The best maple trees to tap are 30- to 40-year-old sugar maples, silver maples, red maples, black maples and box elder trees.