"After you give him the boneknit [...] you wrap the broken limb in toweling soaked in water where you’ve boiled blue goatflowers - only the blue, mind! [...] and as hot as he can stand it. One part blue goatflowers to ten of water, no weaker. Replace the towels as soon as they stop steaming, and keep it up all day. The bone will knit twice as fast as with boneknit alone, and twice as strong."
In short, made in a hot poultice and water, boiled blue goatflowers improves the healing of broken bones.