Creating Natural Dye Baths from Kitchen Waste

Your Kitchen Already Holds a Dye Garden

Every week, most of us throw away material that would have delighted a dyer two hundred years ago. Onion skins, avocado stones, used tea leaves and coffee grounds all hold colour, and with a saucepan, some water and a little patience you can coax it out. The results are rarely the sharp, saturated hues of a chemical dye — they are softer, more changeable, closer to the colours you see in old tapestries or faded garden twine. That subtlety is precisely the point.

Natural dyeing suits small projects beautifully: a skein of wool for a woven panel, a metre of cotton to cut into strips for a willow frame, a handful of embroidery threads. Work in small batches, keep notes, and treat each result as an experiment rather than a production line.

What to Save, and What Each Scrap Gives You

Start a dedicated jar or bag in the freezer and add to it as you cook. Frozen scraps dye just as well as fresh ones.

• Brown onion skins — the workhorse. Expect warm amber, gold and rust, deepening to olive-brown with an iron modifier. Roughly two large handfuls per litre of water.
• Red onion skins — softer, pinker tones, sometimes with a greenish cast on wool.
• Avocado stones and skins — a gentle dusty pink through to soft beige. They need a long simmer to give up their colour.
• Used tea leaves and tea bags — warm tan and biscuit browns straight from the pot, and on wool they need no mordant at all.
• Coffee grounds — soft brown and grey-brown, especially good on cotton.
• Carrot tops, parsley stalks and spinach — pale yellows and greens, though these fade quickly in sunlight.

Be realistic about lightfastness. Onion skins, avocado and tea are reasonably stable. Beetroot, blueberry and turmeric give glorious colour that will fade within weeks on a windowsill, so save those for items that never sit in direct sun.

The Kit, and Why a Mordant Matters

Colour needs something to grip. A mordant is a metal salt that binds dye to fibre, and without one your colour will wash straight out. The safest and most reliable for home use is alum (aluminium potassium sulphate), used at roughly 10–15% of the dry weight of your fibre. A pinch of cream of tartar added alongside brightens the result.

• A stainless steel or enamel pan, kept solely for dyeing — never one you cook food in.
• A wooden spoon or long-handled tongs, also kept for dyeing only.
• A fine sieve or a square of muslin for straining.
• A jam thermometer, if you have one; keeping the bath below a simmer gives cleaner colour.
• Rubber gloves, especially if you make iron water.

Wool and silk are protein fibres and take up dye far more readily than cotton and linen, which are cellulose. For cotton, pre-treat with a tannin bath — a strong brew of used tea leaves works well — then mordant as usual.

A First Bath, Step by Step

• Weigh your dry fibre, then weigh out your alum at 10–15% of that figure.
• Soak the fibre in lukewarm water for an hour so it wets through evenly.
• Simmer your scraps in water for 30–60 minutes — longer for avocado stones — then strain out the solids.
• Add the alum, stir to dissolve, and lower in the wet fibre.
• Hold the bath at 80–90°C for an hour, stirring gently and often. Never let it boil hard, which dulls wool and can felt it.
• Turn off the heat and leave the fibre in the pan overnight. This slow cooling deepens the colour considerably.
• Rinse in water of gradually decreasing temperature until it runs clear, then dry in the shade.

Tweaking the Shades

One bath can give you several colours. Divide the strained liquid and modify each portion separately.

• Iron water — a jar of rusty nails topped up with equal parts water and white vinegar, left for a fortnight. A tablespoon per litre "saddens" colours, turning gold to olive and pink to grey. Use it sparingly, as too much harms the fibre.
• Bicarbonate of soda — a pinch shifts colours warmer and deeper.
• Vinegar — a splash brightens the bath and shifts pinks and yellows.

Always modify the dye bath before adding fibre, and test on a small sample first so you do not commit a whole skein to a shade you dislike.

Weaving Your Colours Into Garden Craft

These soft skeins sit happily alongside willow. Dye narrow strips of cotton or linen and weave them through the framework of a willow obelisk or plant support, or twist dyed wool around a wreath base for a gentler, more textured finish. Dyed raffia works beautifully for tying in sweet peas and training young climbers, and it looks far better in a border than bright plastic twine.

Wash dyed pieces by hand in cool water with a pH-neutral soap, dry them in the shade, and expect a little colour to release over time — this is part of the character of natural dye rather than a fault. Label your skeins with the date and the bath you used. A small notebook of onion-skin golds and tea browns, built up over a season, becomes a genuinely useful record of your own garden-craft palette, and next spring you will know exactly which scraps to save.