Shevat

Shevat is the eleventh month of the Hebrew year, falling in late winter, roughly January to February, and aligned in tradition with the sign of Aquarius. It counts thirty days. Its fifteenth, Tu BiShvat, is the new year of the trees, a date fixed in the Mishnah for reckoning the age of trees for tithing and now widely kept as a celebration of nature and, in modern times, of ecology, marked by eating the fruits of the land of Israel. The name Shevat was adopted in the Babylonian period. The Hebrew calendar is lunisolar, its months following the moon while an added leap month keeps them aligned with the solar year. These are the observances of the Jewish calendar tradition, in which Shevat, though deep in winter, looks ahead to spring through the new year of the trees.

Shevat holds Tu BiShvat, the fifteenth, the traditional new year for trees, a date the Mishnah fixes for calculating the age of fruit trees for tithing purposes under biblical agricultural law rather than as a nature festival in its own right, though in modern practice, particularly since the twentieth-century revival of Hebrew agricultural symbolism in the Land of Israel, it has become widely observed as an ecological and tree-planting occasion. The date's position in late winter in the Northern Hemisphere, when the earliest-blooming trees in the Land of Israel's own climate, notably the almond, begin to flower, underlies the Mishnah's original choice of this point in the year as the fiscal cutoff for tree-tithing calculations.

The name comes from the Akkadian Shabatu, one of the Babylonian month names adopted wholesale into Hebrew usage. The month runs a fixed 30 days in every year.

The month names are Babylonian. Twelve of them are the Akkadian month names taken into Hebrew during and after the exile, and the biblical books of the return use them freely while the earlier books generally number the months or use a small set of older Canaanite names. The atlas records the borrowing rather than presenting the names as native, because it is one of the clearest visible marks the exile left on Jewish practice.

The Jewish calendar as now kept is calculated rather than observed. Month lengths are fixed by rule except for Cheshvan and Kislev, which absorb the adjustment and may run 29 or 30 days, and a thirteenth month is added in seven years out of nineteen on a fixed cycle so that Passover stays in the spring. A further set of rules, the postponements, shifts Rosh Hashanah off certain weekdays, which is why the year has six possible lengths rather than two.

Shevat contains Tu BiShvat, the fifteenth of the month, called the new year of the trees. The Mishnah lists four separate new years in the Jewish calendar, of which this is one, which is a useful corrective to the assumption that a calendar has a single beginning.