symbol of rebirth
At the thirteenth day of Nowruz, known as Sizdah Bedar, the sabzeh is thrown into running water (the sabzeh grown for the Haft-seen believed to have symbolically collected all sickness and bad luck) to exorcise the demons from the households. It is also customary for young single women to tie the leaves of the sabzeh before discarding it, and express a wish to be married before the next year's Sizdah Bedar.
Preparing and growing the sabzeh are usually done a few weeks before the New Year. However, if one's hands are simply far from 'green' to prepare for oneself, pre-grown sabzehs are abundantly and readily available at most Iranian stores and along the street's stalls even at the very last hour.