Arbor Day fifteenth day of the month Esfand, which usually corresponds with March 5. This day is the first day of the "Natural Recyclable Resources Week" (March 5 to 12). This is the time when the saplings of the all kinds in terms of different climates of different parts of Iran are shared among the people. They are also taught how to plant trees. The Jewish holiday Tu Bishvat, the new year for trees, is on the 15th day of the month of Shvat, which usually falls in January or February. Originally based on the date used to calculate the age of
Leap year lunar months containing 29 or 30 days, generally in alternating order. However, the tabular Islamic calendar used by Islamic astronomers during the Middle Ages and still used by some Muslims does have a regular leap day added to the last month of the lunar year in 11 years of a 30-year cycle. This additional day is found at the end of the last month, Dhu 'l-Hijja, which is also the month of the Hajj. The Hijri-Shamsi calendar, also adopted by the Ahmadiyya Muslim Community, is based on solar calculations and is similar to the Gregorian calendar in its structure with