To put simply phenology is the timing of a natural process throughout the 4 seasons. A tree has 5 major stages, which I shall detail below:

Stage 1 Spring

Onset of growth (wake up)

Stage 2 Spring

Formation of new leaves (get dressed)

Stage 3 Summer

High photosynthetic period (eat)

Stage 4 Summer – Autumn

Formation of new bark and wood (work)

Stage 5 Winter

Dormancy (rest)