Tehran Municipality's department for Parks and Greenspace organises the event.
According to head of the department, Ali Mohammad Mokhtari, 250 domestic and 39 foreign producers of flowers and related products are taking part.
For local growers, it's a chance to showcase their work. But for attendees it's a welcome opportunity to reconnect with nature.
"Apartment living has minimised people's contact with flowers and plants," says Tehran resident Arzhang Habibzade, who's visiting the show with his wife. "Such shows make us be in touch with nature more often and care about it. Maybe they can even make us move to more natural-looking places."
This year is the 13th edition of the 'Tehran International Exhibition of Flowers, Plants, Parks Equipment & Related Industries.
Organisers say an aim is to encourage attendees to grow flowers of their own in their apartments.
"Unfortunately flowers have a smaller role in the modern, machine life compared to the past, especially in Iranians' lifestyles," says show visitor, Pazooki. "Such a show, held once or twice a year, is good, but I think many more shows should be held in various locations so that people can have easier access."
The 13th Tehran International Exhibition of Flowers, Plants, Parks Equipment & amp;amp; Related Industries runs 11-15 May 2015