Herbalism 1–450: Leveling (WotLK)

How to quickly raise Herbalism to 450 on WotLK 3.3.5a: where and what kind of herb to collect and why it is one of the most profitable professions.
Briefly
The herbalist collects herbs (fuel for Alchemy and Inscription) and receives “Lifeblood” - heal + acceleration for 20 sec. Pure collection, without crafting: it increases as you drive through locations.
Leveling up by segments and locations
1–75
- Peacebloom, Silverleaf, Earthroot - starting locations (Elwynn, Durotar).
75–150
- Mageroyal, Briarthorn, Bruiseweed - Barrens/Ashenvale.
150–225
- Kingsblood, Liferoot, Fadeleaf - Darkshore/Swamp.
225–300
- Goldthorn, Khadgar's Whisker, Sungrass - Highlands/Feralas/Un'Goro.
- Black Lotus - raid zones (rare, expensive).
300–375
- Felweed, Dreaming Glory, Terocone - Outland (Zangar, Nagrand).
375–450
- Goldclover, Deadnettle, Tiger Lily, Talandra's Rose, Lichbloom, Icethorn - Northrend.
- Frost Lotus is a rare WotLK flower, most valuable at auction.
Tips
- Fly along the spawn spots and visit the skill trainer every 75.
- Sell herbs in bulk - Alchemists and Inscribers take a lot.
- Lifeblood is useful for tanks and in PvP as a free save.
Summary
Herbalism is the best “farm without hitting”: carry a stack of herbs and level up at the same time.