The following is a recipe taken from the Wàn Bìng Huí Chūn 萬病回春, an herbal compendium written by Gon̄g Tíngxián 龔廷賢 during the Míng 明 dynasty. The translation and accompanying commentary are mine.
The recipe describes a fruity tasting, alcoholic herbal preparation which is meant to be drunk at the most yīn 陰 time of year in order to nourish the most yīn 陰 aspect of the body. It could be said that the hair, beard, and moustache are all yáng 陽 expressions of this yīn 陰. From a modern clinical perspective, this formula is good "kitchen medicine" for anyone - whether male or female - who would like to take a deeply nourishing, moistening, and slightly invigorating tonic. It is especially appropriate for persons over 50.
If you are outside China, you will likely have to replace fresh goji berries with dried ones. This is fine, but be sure to rehydrate them and break them up before adding the alcohol.
The Translation: Clean Copy
Empirical Formula to Blacken the Hair
This formula can change white hair to black and make the body feel light and healthy. Its merits cannot be fully told. Every year, on the 9th or 10th day of the 10th lunar month, face east and pick red, plump goji berries (1 liter sic). Smash. Add a good, dreg-free wine (1.2 kg sic) and let soak together in a stoneware bottle for 21 days. Once enough time has passed, open the seal and add fresh rehmannia root (1.8 kg). Mix evenly. Then use three layers of paper to seal the mouth of the bottle. Let sit until 30 days prior to Lì Chūn, and then open the bottle. Take daily on an empty stomach: drink 1 warm cup. Once Lì Chūn has passed, the moustache and beard will be both be black. Do not each turnips, onions, or garlic during this time. Take this formula in order to prove its effectiveness. If it is taken every year, one will endure old age with an incomparably light-feeling body.
 Annotated copy, below.
 "Blacken" makes sense in context (i.e., Chinese people typically have black hair). If your hair is blonde, for example, this formula will not change your hair color to black, but will slow the greying process. In some cases it does actually reverse process. Nonetheless, expectations should be tempered.
 The timing is based on the Chinese lunar calendar. For ease sake, follow the timing described in note .
 Likely referring to a rice-based wine, but feel free to use whatever you'd like. Please remember, though, that the liquid medium must contain alcohol if it is to be an effective tincture.
 Do NOT substitute Western foxglove root (significant toxicity).
 Classically, Lì Chūn 立春 referred to the period of time starting at the new moon at Chinese New Year. It literally means "Establishing Spring". I'll save a discussion about why spring is "established" in the dead of winter for another time.
 This formula should be taken daily for an entire moon cycle before Chinese New Year. In 2018, Chinese New Year is February 16th. Since there is an intercalary lunar month in January, the calculations are somewhat challenging, but - if I've got it right - this means that one should mix the goji berries with the alcohol on the first quarter moon of November 26th, add the fresh rehmannia root on the new moon of December 17th, start taking on the preparation on the new moon of January 16th, and finish taking the preparation on the new moon of February 15/16th.
 In classical Chinese herbal texts, the turn of phrase "empty heart" 空心 actually means "on an empty stomach".
 Also, newly-grown head hair.
The Translation: Annotated Copy
Empirical Formula to Blacken the [Hair]
[This formula] can change white [hair] to black and make the body feel light [and] healthy. Its merits cannot be fully told.
Every year, on the 9th or 10th day of the 10th lunar month, face east and pick red, plump gǒu qǐ [zǐ] 枸杞[子] goji berries (12 shēng 升 [roughly 1 liter]). Smash. [Add] a good, dreg-free wine (2 jīn 斤 [roughly 1.2 kg sic]) and let soak together in a stoneware bottle for 21 days. [Once] enough [time has passed], open the seal and add shēng dì huáng 生地黃 fresh rehmannia root (3 jīn 升 [roughly 1.8 kg]). Mix evenly. Then use three layers of paper to seal the mouth [of the bottle. Let sit] until 30 days prior to Lì Chūn, and then open the bottle. [Take daily] on an empty [stomach]: drink 1 warm cup. Once Lì Chūn has passed, the moustache and beard will be both be black.
Do not each turnips, onions, or garlic [during this time]. Take [this formula in order to prove] its effectiveness. If it is taken every year, [one will] endure old age with an incomparably light-feeling body.
Thanks for reading!
This post was written in answer to a request. If you have a request for a particular herbal discussion, please let me know in the comments. Nothing in this post should be taken as medical advice. Avoid taking Chinese herbs while on blood thinning medications. To schedule a consultation, please contact me at [email protected]
Criticism appreciated: Teach me more Classical Chinese.
Chinese text from http://www.theqi.com/cmed/oldbook/book117/index.html
Images from https://pixabay.com and from http://www.threefieldsacupuncture.com