Harvest timing depends on the plant part you want, the species, and your intended use. Work from clean, correctly identified plants and avoid harvesting material that is diseased or contaminated.
Flowers
Collect flowers when they are fresh and in good condition, then process promptly so they do not sit warm and damp.
Leaves
Choose healthy foliage and avoid taking so much that the plant cannot recover.
Roots
Root harvest is more disruptive and often ends or sets back the plant. Confirm species-specific timing before digging.
Record what you harvested
Label plant material immediately with plant name and date. Accurate identification matters more than decorative storage.