A Quiet Harvest by the Water

There is a particular stillness that comes from walking a brook in late summer with a basket on your arm. The water runs low, the banks are loud with insects, and the plants growing along the edge — the ones we usually pass without a second glance — are quietly full of colour. Dyeing with them is slow work, and that is precisely the point. It asks you to notice, to gather lightly, and to wait.

None of it requires expensive equipment. A pan you no longer cook with, a bucket of rainwater, a wooden spoon and a few plants are enough to begin.

Three Faithful Plants: Alder, Meadowsweet and Nettle

All three grow abundantly along British streams and rivers, which makes them a kind and sustainable place to start.

• Alder (Alnus glutinosa) — the cones and bark are rich in tannin. Gather fallen cones from the ground, or last year's dried ones still on the branch; never strip bark from a living trunk. Alum-mordanted wool gives warm tans and soft browns, and a dip in iron turns them khaki, then near-black.
• Meadowsweet (Filipendula ulmaria) — the frothy cream flowers give a gentle yellow on wool. The roots, historically used to make black, yield deep browns and greys with an iron modifier. Dig nothing, though: pick a few flower heads from a generous stand and leave the roots in peace.
• Nettle (Urtica dioica) — the most obliging of all. A carrier bag of leaves and stems, simmered, gives yellow-green on alum-mordanted wool; add iron and it deepens into a rich olive-grey, the colour of the riverbank itself in October.

Take no more than a tenth of any patch, avoid nature reserves and sites of special scientific interest, and never gather from the same stretch twice in one season.

Preparing the Dye Bath

Weigh your fibre dry before you begin; every quantity that follows is a percentage of that weight, which dyers call WOF — weight of fibre.

Chop or tear the plant material roughly. For a good depth of colour, use roughly equal weight of fresh plant to fibre, or half that if dried. Put it in your dye pan, cover with rainwater — soft water gives clearer colours than hard tap water — and bring it slowly to a gentle simmer. Nettle needs about an hour; alder cones and meadowsweet flowers are content with forty-five minutes to an hour. Then take the pan off the heat and let it steep overnight. Straining the liquor before you add the fibre keeps your yarn free of plant debris.

Mordants, and How to Use Them Safely

Mordants are what fix colour to fibre, and they deserve respect. Keep a dedicated pan, spoon and set of scales for dyeing only, and never use them for food again. Wear gloves, work outdoors or in a well-ventilated space, and store powders in labelled jars well away from children and pets.

• Alum (potassium aluminium sulphate) is the safest and most forgiving mordant. Use 10–12% WOF, plus 6% cream of tartar. Dissolve in hot water, add damp fibre, hold at around 80°C for an hour, then cool overnight in the liquor.
• Iron (ferrous sulphate) is a modifier rather than a mordant. Use it sparingly — 1–2% WOF at most — in a separate pot, dipping the dyed fibre briefly to sadden the colour. Overuse makes wool brittle.
• Tannin from alder cones or oak galls helps plant fibres such as cotton and linen take up alum, so treat those with a tannin bath first.

Wool and silk are the easiest fibres for beginners; they take up colour readily and forgive a slow hand.

Colours Worth Waiting For

Dyeing with riverbank plants is not a fast route to a bright, uniform shade. It is a route to the colours of one particular summer — a soft green-gold, a brown the colour of a heron's wing, a grey that shifts in different light. Expect variation between batches, and welcome it. Add the fibre to a warm, strained dye bath, bring it gently to 80°C, hold it there for an hour, then let it cool completely in the pan before rinsing in water of the same temperature, which helps to avoid felting.

Dry your skeins in the shade, and they will keep their colour for years if you store them away from direct sun.

Keeping Notes, and Giving Back

Write down the date, the plant, the quantity, the mordant, the water and the result. A small notebook soon becomes your real teacher; two years of notes will tell you more than any recipe. Then return to the brook. Leave the banks as you found them, take your litter home, and let the meadowsweet stand to seed. The slow pleasures of this craft — the walk, the simmering pan, the first glimpse of colour on wet wool — are the same pleasures as the riverbank itself. Give it time, and it will keep giving.