This is the first phase of growth. New cells are formed by the division of meristematic cells. The meristematic cells are thin walled, isodiametric and have dense non vacuolated granular cytoplasm together with a prominent nucleus. Cell division for growth is always mitotic hence it is also called vegetative cell division (meiosis is called reproductive cell division).
Synthetic activity will be maximum before mitotic cell division, as extra materials have to be produced to be distributed between the two will be smaller than the parent cell and they have to pass through the next two stages before they become an integral part in the structure and function of the plant system.