Tu Bishvat takes its name from the date of its observance on the Hebrew calendar—the 15th day of the month of Sh’vat, which falls in January or February. Tu Bishvat is also known as the New Year for Trees, which is how it is described in the Mishna (Rosh Hashana 1.1) because it is the date from which the age of trees was counted, determining when fruit tithes were owed in the days of the Temple. This date was selected because trees flowered after it. In Israel, where the winters are relatively mild, the date also marks the beginning of the tree-planting season.