Most flowers can be said to last for around 7-10 days.  

The life of flowers is  dependant upon what flowers you have.   As a general rule of thumb flowers perform best when in season.   However, with technology in the flower industry pushing forward, most flowers are available all year round.

Lilies will go on for 10-14 days as will amaryllis and orchids when in season.   Chrysanthemums and blooms will last for around 7-10 days.   Roses go on for 7-10 days.   However, Columbian roses can last for 10 days +.