Take a quart of Lye prepared from the Ashes of Vine-twigs; Briony, Celandine Roots, and Turmeric, of each half an ounce, Saffron and Lilly Roots, of each two drachms; Flowers of Mullein, Yellow Steebas, Broom, and St. John’s wort, of each a drachm; boil these ingredients together, and strain off the Liquor clear. Frequently wash the hair with this fluid, and in a little time it will change to a beautiful flaxen colour.
The Toilet of Flora, 1772.
This is one 18th century recipe that would probably work… but caustic lye is NOT something you want to put on your hair, or anywhere near your skin! In its pure form it will give you severe chemical burns.
The other ingredients aren’t too bad; saffron and turmeric are used to make a yellow dye.