The traditional Nowruz holiday period in Iran lasts 13 days.
The celebration culminates on the thirteenth day of Farvardin in the festival known as Sizdah Bedar, often called Nature Day. Families traditionally leave their homes, spend time outdoors, and picnic in parks, fields, or other natural settings. This day marks the end of the Nowruz holiday period.
The first several days include visiting relatives, exchanging good wishes, and observing the New Year. Iran’s legal public-holiday schedule is narrower than the full traditional observance: the opening days of Farvardin are official holidays, while Sizdah Bedar is also recognized as a holiday. Thus, “13 days” describes the customary Nowruz holiday period, not necessarily 13 consecutive days with identical government-office closures.
A well-known Sizdah Bedar custom is releasing the sprouted greens, or sabzeh, used in the Haft-sin display, sometimes into running water. People may also knot the greens while making wishes before discarding them. The number 13 refers to the thirteenth day of the festival, not to Nowruz’s date on the Gregorian calendar.