The Nowruz celebration lasts at least two weeks.
It starts on the last Tuesday before the equinox and continues for thirteen days after the equinox.
And on the 13th day of the new year, people take their sabzeh...
(Sabzeh is one of the seens - https://afarinrava.blogspot.com/2022/03/haftseen.html)
...and go out for a picnic, where they spend a few hours and leave their sabzeh behind.