Question: How do I know when the marijuana vegetative stage is over?
Answer: When the marijuana plant is in the vegetative stage, it only grows vegetative growth like leaves and stems.
In the vegging stage, the plant does not grow buds/flowers at all.
You can tell when the vegetative stage has ended because the plant starts growing gender-specific parts in addition to leaves and vegetative growth.
For example, you know the flowering stage has started when the plant starts growing pistils/white hairs/buds if plant is a girl, and balls/pollen sacs if a boy.
Vegetative Stage vs Flowering Stage Diagram