Horizon Forbidden West has 3 Dyer Locations. Dyers are special merchants that let you customize the color of your outfit (armor). They are found in the three settlements Plainsong, Scalding Spear, Thornmarsh. None of them are missable, you can still visit them after the story in free-roam.
Talk to the Dyers to see what color customizations they have available for your outfits. Most dyes cost flowers (also called “blooms” in-game). You find these everywhere alongside mountain walls. You must climb up to collect them from climbable mountainsides. Wherever there’s a long mountain wall, there will be some blooms to find. More on this in the section at the end of the page.
Customizing at least one outfit with blooms/flowers at a Dyer unlocks the trophy “Used Dye Flowers”.
Dyer Locations
Dyer #1: Plainsong
Dyer #2: Scalding Spear
Dyer #3: Thornmarsh
Where to Find Flowers for Dyers
Practically anywhere there’s a long mountain wall, you can find blooms alongside the climbable rocks. The blooms only grow on the side of mountains, they are never found on the ground. Below is a wall where you can find plenty of flowers of various types. Any other mountainous area will work too. You can fast travel to a campfire in a mountainous area, follow the mountainside and scan with R3 for any blooms.
For anything else needed to 100% completion, check out the full Horizon Forbidden West Wiki & Strategy Guide.
There’s one in The Bulwark too