Thyme can help promote hair growth by both stimulating the scalp and actively preventing hair loss. Like cedarwood oil, thyme oil was also found to be helpful in treating alopecia areataTrusted Source.

Thyme is particularly strong, even among essential oils. Put only 2 small drops in 2 tablespoons of a carrier oil before applying it to your scalp. Leave it on for about 10 minutes, then wash it out.