Dyeing Yellow with Yarrow — The Ancient Wound-Herb of Every Meadow

Use 200% WOF of fresh yarrow, or 100% WOF dried. For 100 g of wool, gather 200 g of fresh flowering tops or 100 g dried. Harvest when the flowers are fully open — peak bloom gives the strongest yellow. Cut the upper 15-20 cm of the plant, including flower heads and upper leaves. Both flowers and leaves contain dye, but the flower heads are richest. Yarrow is easy to identify: feathery, finely divided leaves (hence 'millefolium' — thousand leaves) and flat-topped clusters of small white or pale pink flowers. Avoid any plant you cannot positively identify.

Place the yarrow flowers and leaves in a dye pot with 4 litres of warm water and soak for at least one hour. The water will turn a pale greenish-yellow as the flavonoid pigments begin to dissolve. Fresh yarrow releases colour faster than dried. If using dried yarrow, extend the soak to 2-3 hours or overnight for best extraction. The aromatic, slightly medicinal scent of yarrow will be noticeable during soaking.

Bring the pot to a gentle simmer (75-80°C) and hold for 30-40 minutes. Stir occasionally. Do not boil — excessive heat degrades the delicate flavonoid yellows toward dull brown. The liquid will deepen to a warm golden-yellow. The flower heads will lose their colour and turn brownish as the pigment transfers to the water. Yarrow has a pleasant herbal aroma during simmering — far more agreeable than some dye plants.

Strain the dye liquor through a fine mesh strainer into a clean pot. Press the plant material to extract all remaining yellow liquid. Yarrow flowers and leaves become soft and pulpy during simmering — strain thoroughly to prevent fragments from tangling with the wool. The strained liquor should be a clear, warm golden-yellow.

Pre-wet the alum-mordanted wool in lukewarm water for 15 minutes, squeeze gently, and lower it into the yarrow dye bath at room temperature. Slowly raise to 80°C over 15 minutes, then hold for 45 minutes. Turn gently every 10 minutes. The wool will develop a warm, clear yellow — soft golden in tone, less green than nettle and less vivid than weld, but with a pleasant warmth. The alum mordant is essential for good colour uptake and fastness with yarrow.

Turn off the heat and let the wool cool in the dye bath overnight. Remove, squeeze gently, and rinse in lukewarm water until the runoff is clear. The final colour is a warm, soft yellow — the colour of late summer meadows where yarrow blooms. Lightfastness is moderate — better than marigold or dahlia, but not as permanent as weld. The luteolin content gives yarrow better longevity than most flower-based yellows. With prolonged sunlight exposure, the colour will gradually soften but retains a warm tone rather than greying. Dry in shade.