That way, you can choose an essential oil according to its function:
Basil strengthens and restores hair. I can only stand the smell when it is very faint though. Just as well as it is better for oily hair types.
Bergamot strengthen thin, dull weak hair. So you may see it my "Love Me" recipes (for weak/brittle/damaged hair) or "Adore Me" recipes (for thin/thinning hair).
Cedarwood stimulates the scalp and promotes hair growth. Helps to treat hair loss and dandruff. Improves hair health.
Chamomile adds shine and softness to hair, and soothes the scalp. I've found many references with regards to it lightening blond hair but I'm not sure if it changes the color of black hair, hmmm?
Clary sage promotes hair growth and stimulates the scalp.
Geranium strengthens hair.
Lavender is regenerative, stimulates hair growth, deep conditions hair, keeps it shiny, and helps control dandruff. Lavender is a total all-rounder - add it to anything.
Orange & Mandarin - amazing scent, fresh scent! It's not widely known for any other hair benefits.
Patchouli alleviates dandruff and balances excessive oiliness. Better for oily hair types.
Peppermint very soothing to the scalp so I use it in all my "Soothe Me" recipes.
Rose hydrates hair and promotes hair health but it is super, super expensive. Apparently it takes 200 rose petals to make a single drop of the oils!
Rosemary oil stimulates the roots, improves hair growth, softens hair and soothes the scalp, prevent premature greying. That's why I also use rosemary in my Sage And Rosemary Hair Rinse. Better for oily hair but because of all its benefits I consider it a staple.
Sage helps with scalp issue like psoriasis.
Sandalwood oil helps with dry ends, and adds fragrance to the hair.
Note that when it comes to hair growth you will find lots of essential oils associated with it. However, I have only seen scientific studies confirming hair growth for four essential oils: rosemary, lavender, thyme and cedarwood. This is why they are all in Neno Natural's Hair Growth Stimulator.