St. John’s Wort is best known as a medicinal plant, used for centuries as a remedy for melancholy, nervousness, and sleeplessness, hence its long association with “the blues.” Beyond its healing reputation, this common wildflower also offers a remarkable palette for the dyer. From golden yellows and greens to delicate pinks and reds, the colour outcome shifts dramatically depending on mordant choice and bath pH.

Historical Note
Across Europe, St. John’s Wort was gathered around midsummer (St. John’s Day) and hung in homes for protection. Its strong folk presence as both medicine and ritual plant extended naturally into dye use, where dyers discovered its unusual sensitivity to acidity: a single adjustment could turn a golden bath toward shades of rose or rust.

Active Coloring Compounds Naphthodianthrones (including hypericin) and flavonoids.

CI Colour Name
Closest family: CI Natural Yellow 8 / Natural Red 22 (not formally listed in the Colour Index but aligning with these natural dye families).

Shading Tips

• Alum mordant → bright yellows, clear greens
• Ferrous sulfate → olive greens, deeper tones
• Acidic bath → pushes colours toward pinks and reds
• Neutral/alkaline bath → favours yellows and greens