There is a moment in late spring when the nettle patch behind the compost heap is at its tender best, and a moment in October when acorns start clattering onto the path. Both are worth putting in a pan. Dyeing with British plants is slow, forgiving and remarkably cheap: you need a pot you no longer cook in, a few handfuls of foraged material and some patience. The colours are not the flat, uniform shades of a shop-bought dye — they are softer, slightly unpredictable, and they shift with the season, your water and the fibre you choose. Here is how to start with three of the easiest plants going: nettles, onion skins and acorns.
First, the Kit — and the Rule About Pans
Once a pan has held a dye bath or a mordant, it never goes back to the kitchen. Keep a separate set: a large stainless steel or enamel pot, a wooden spoon, a sieve, a jug, a thermometer, kitchen scales and a few glass jars with lids. Aluminium reacts with dyes and dulls colours, so avoid it. Chipped enamel is best avoided too, as the iron underneath can affect your results.
Soft water gives clearer colours. If your tap water is hard, rainwater is worth collecting, though hard water will still work — it just tends to mute the brighter yellows.
Preparing Fibre: Protein Versus Cellulose
Dye plants split their favours between two families of fibre. Protein fibres — wool, alpaca, silk — take colour readily and are the easiest place to begin. Cellulose fibres — cotton, linen, hemp — need more persuading, usually a tannin pre-soak before mordanting. Either way, the fibre must be scoured first, because invisible oils and manufacturing residues block dye from bonding.
- Wool and silk: soak in lukewarm water with a squirt of gentle, pH-neutral soap for twenty to thirty minutes. Do not rub or wring. Rinse in water of the same temperature, as sudden changes make wool felt.
- Cotton and linen: simmer for thirty to sixty minutes with a teaspoon of washing soda per litre of water and a little detergent. This strips the pectins and finishes that would otherwise resist dye.
- Both: rinse until the water runs clear, then mordant while the fibre is still damp. Dry fibre takes up mordant unevenly.
Mordanting Without the Worry
A mordant is a metal salt that acts as a bridge, holding dye molecules onto the fibre so they do not simply wash out. Alum — potassium aluminium sulphate — is the workhorse for beginners: it gives clear, bright colours and is the least troublesome to handle. Cream of tartar, added alongside, softens the feel of wool and helps colours stay clean.
A common starting point is roughly 10 per cent alum to the dry weight of your fibre, plus about 5 per cent cream of tartar for wool or silk. Dissolve the powders in hot water, top up the pot so the fibre can move freely, add the wetted fibre, then heat slowly to around 80°C and hold for forty-five to sixty minutes. Let it cool in the bath, lift it out and use it damp. Cellulose fibres usually want a little more alum, and a tannin pre-soak beforehand.
A few sensible precautions. Wear gloves and a dust mask when handling powders, label every jar, and keep them well away from children and pets. Never pour mordant baths down the drain or tip them onto the vegetable bed in quantity. Copper and iron in particular are harmful to aquatic life, so dilute heavily, use the smallest amounts you can, and check with your local authority if you are unsure how to dispose of a batch.
Nettles: Soft Greens From a Weed
Pick young nettle tops in spring, before the plants flower, taking the top four leaves and wearing gloves. Seeded nettles in high summer give duller, yellower tones and the stems are coarse. Use roughly twice the weight of fresh nettles to fibre — they are free, so be generous. Chop them roughly, simmer for forty-five minutes to an hour, strain out the plant matter, then add your damp mordanted fibre and hold it at 80°C for an hour. Leave it to cool overnight in the bath for deeper shades.
On alum-mordanted wool, nettles give a soft sage green with grey-yellow undertones. Dip the skein briefly in iron water — rusty nails steeped in vinegar and water for a week or two — and it deepens to olive. Go carefully with iron: too much dulls the colour and can weaken fibre over time. On cotton, expect something paler and more yellow unless you have tannin-treated it first.
Onion Skins: The Reliable One
Keep a paper bag in the kitchen and fill it all year with the dry outer skins of yellow, brown and red onions. This is the dye to try first, because it is almost impossible to ruin and it works on wool and cotton alike. Roughly the same weight of skins as fibre is a decent starting point; more skins means a deeper colour. Simmer the skins for thirty minutes, strain, then add the fibre and hold as above.
Yellow onion skins on alum give a warm gold that slides towards amber and rust with a longer simmer. Red onion skins tend towards olive-tan. A pinch of washing soda in the bath will shift colours greener; a splash of vinegar will warm them up. Iron produces a deep olive-brown; copper gives a muted green, though copper sulphate is toxic to aquatic life and best left alone unless you know exactly what you are doing.
Acorns: Tannin, Browns and Near-Blacks
Gather acorns in autumn, caps and all, and leave plenty behind — they feed jays, squirrels and deer. Crush them with a hammer or under a sturdy boot, then simmer for an hour or two, or cold-soak for a week for a gentler brown. The liquor looks like strong tea and smells earthy, so open a window.
Acorns give warm mid-browns on their own, and grey through to charcoal-black when iron is involved. Because they are so rich in tannin, the same bath doubles as a pre-treatment for cotton and linen before alum mordanting. Oak bark, gathered sparingly from fallen branches rather than stripped from living trees, gives similar tones with a redder edge.
A Year of Colour, and a Notebook
Foraging follows the calendar. Spring brings nettle tops, dandelion root and gorse flowers. Early summer offers meadowsweet and the last good nettles. Late summer gives yarrow and marigold. Autumn is the richest season: acorns, oak bark, walnut husks, rosehips and windfall apples. Winter is for using up stored onion skins and dyeing blacks with iron. Leave lichens alone — they grow too slowly to harvest responsibly.
Write everything down: date, plant, weight of material, weight of fibre, water, mordant, temperatures, timings and the finished colour. Attach a labelled sample of yarn to each note. Without a record, a colour you love becomes impossible to repeat, and the small variations are half the pleasure of the craft.
Your First Pot: A Simple Plan
- Choose one protein fibre — a 50g skein of undyed wool is ideal — and scour it.
- Mordant with alum and cream of tartar, then leave it damp.
- Simmer a bag of yellow onion skins for half an hour in a dedicated pan.
- Strain, add the fibre, hold at 80°C for an hour, then cool overnight.
- Rinse gently in cool water, dry in the shade, and note down everything you did.
Change one thing next time: a longer simmer, a splash of iron water, a different fibre. To check how well a colour holds, hang a small sample in a sunny window for a fortnight and compare it with one kept in a drawer. Natural dyes often soften rather than vanish, which is part of their charm. Start with onion skins, move on to nettles when the spring patch is ready, and save the acorns for a wet October afternoon.
Photo: Hans / Pixabay
