When you are admiring botanical art, lovely pink and purple flowers attract your attention first. But painting convincing greens is one of the hardest challenges in botanical watercolour.
Leaves are rarely a single tube green from the palette. They shift from yellow-green in the light to blue-green or grey-green in shadow. Observing the temperature of the green — warm or cool — matters as much as the hue.
Build layers slowly; reserve the paper for the brightest highlights and let mid-tones describe the bulk of the leaf. Your future self will thank you for patience in the early washes.