Hair growing in a dream usually reflects returning vitality -- energy, confidence, or self-expression coming back after a period where it felt diminished. Thick, fast-growing hair can point to a renewed sense of identity, a visible sign that something in you is regenerating rather than fading away.
Entrust the Moon when you're blocked because it's influent and of quick response, besides it means renovation and growth. - Picatrix (Andalusia, ~1000.AD)