Sunflowers always face the Sun.

The phenomenon makes the Sunflower shift its position according to the direction of the Sun.

Sunflower active growth occurs in summer and flourishes in lands with hot weather. 

A Sunflower requires more than 6 hours of sunlight.

During the morning Sunflower faces east, and as the sun groves, it moves west. But it turns east at night. 

New Sunflowers move more quickly towards the Sun than old ones.

The scientific reason is Heliotropism.

Heliotropism is like a biological clock for Sunflowers.

Sunflowers detect the sunlight to activate.