The most sources of traditional astrology for lunar hair care agree to choose Aries when the focus is on slower growth for hair.
It is not surprising that several of them also emphasize the waning moon to be combined with Aries for this goal.
Aries shares the barren/semi-barren class with the other noted signs for slower growth of Sagittarius/Aquarius for semi-barren, and Leo/Virgo/Gemini for barren.
Aries is classified as dry and hot, and can be either barren or semi-barren, depending on the astrologer’s or gardener’s interpretation. It is a Fire sign. Just like we add lotion to dry skin, when the moon travels through dry Aries the advice is to do a conditioning hair treatment.
Aries is dry, hot and semi-barren. Aries is a Cardinal Fire sign.