Why the dye patch belongs with the vegetables

Most of us with a few raised beds or a modest smallholding cannot spare a whole plot for dye plants. The good news is that you do not need to. Marigolds, weld and woad all earn their keep alongside carrots, beans, brassicas and salad, whether by drawing in pollinators, covering ground too thin and stony for much else, or simply filling the awkward strip behind the shed where nothing thrives.

Dye plants are unfussy, and the ones that give the best colour on wool often actively prefer poor soil. Rich, heavily mucked, well-watered ground gives you leafy plants and weak colour. Stingy, gritty, sunny ground gives you concentrated pigment. That makes them ideal tenants for the edges of the plot, where the vegetables never quite get going.

Marigolds: easy colour and a good bedfellow

Calendula officinalis is the sensible place to start. Sow direct in April and May, or in September for plants that will overwinter and flower early the following summer. Thin to about 25cm apart and keep picking. The more you cut, the more you get, right through to the first proper frost.

Use the petals only. The green base of the flower dulls the colour, so pinch the heads and rub the petals free into a bowl. Dried and stored in a paper bag in the dark, they will keep their colour for a year.

• With an alum mordant, petals give soft butter yellows and warm apricots on wool.
• Add a pinch of iron to the dye bath and the same petals turn olive and sage green.
• Roughly 200g of dried petals will dye 100g of fleece to a decent depth.

Traditionally they were planted among carrots and brassicas to confuse pests and bring in hoverflies, and they will happily sit in the gaps between rows without troubling your crop.

Weld: the clearest yellow on wool

Weld, Reseda luteola, is the finest yellow available to a British dyer: clean, bright and remarkably light-fast. It is a biennial, so sow it in June or July in a nursery corner, prick out to about 25cm, and let it overwinter as a low rosette. The following June it throws up tall, slender spikes of pale greenish flowers.

It likes lime and gravel and positively resents being fussed over, which makes it perfect for the stony patch by the gate or along the sunny side of a hedge. Cut the whole stems just as the flowers open and before seed sets, then hang them in bunches somewhere airy to dry.

Use roughly equal weights of dried weld tops and dry wool with an alum mordant for a strong lemon. Weld also overdyes beautifully: a quick dip in a woad vat turns it to a clear green, and repeated dips give the deep green once known as Lincoln green.

Woad: a blue that smells like a farmyard

Woad, Isatis tinctoria, is the one that makes you feel like a proper dyer. It is a biennial too, sown in July or August, but the colour comes from the leaves of the first-year rosette, harvested from July to September. The second year it bolts, flowers and gives you poor colour, so plan to sow fresh each year.

Traditional processing is simple but pungent. Chop the leaves finely, pour over just-boiled water, and leave to steep overnight. The liquid will be a disappointing yellow-brown. Now add soda ash, or a splash of household ammonia, and whisk it hard for several minutes. As it takes up oxygen the vat turns from green to deep blue before your eyes. Keep it at about 50C, add wet wool, and leave it for an hour, lifting it out to air between dips.

• Woad is a brassica relative, so do not follow it with cabbages or kale in the same ground.
• Use a dedicated pan, wear gloves, and work outside or with the window wide open.
• Roughly 250g of fresh leaves will dye 100g of wool a respectable mid-blue.

Fitting them in around the veg

A little planning goes a long way, and the trick is to treat dye plants as useful gap-fillers rather than a separate enterprise.

• Run marigolds along the edges of carrot rows and around the base of a bean wigwam, where they get sun and do not shade the crop.
• Put weld in the thin, dry, stony ground you have given up on, or on the south side of a hedge.
• Give woad its own corner away from the brassica bed, where it can self-seed without becoming a nuisance.
• Add a short row of dyer's chamomile or coreopsis for oranges and golds, and let the tall plants sit on the northern edge so they do not shade the vegetables.

Harvesting, mordanting and a sensible first batch

For wool, an alum mordant is the reliable starting point. Use about 10 to 12 per cent alum by weight of dry fibre, plus a tablespoon of cream of tartar per 100g. Dissolve both in hot water, add wool that has been thoroughly wetted out, and hold the bath at 80 to 85C for an hour. Do not boil it and do not agitate it, or you will felt the fleece. Let it cool in the liquor, then rinse gently.

On quantities, a rough rule for 100g of dry wool is 200g of dried marigold petals, 100 to 150g of dried weld tops, or 250 to 300g of fresh woad leaves. Fresh weights of petals and tops are roughly double the dried figures, so if you are dyeing straight from the garden, weigh generously.

Finally, keep a notebook. Date, plant, mordant, quantities, temperatures, results. Dyeing is a craft of records, and next year's beautiful amber depends on what you wrote down this year. Do not be precious about it either. Pale batches can be overdyed with woad for greens, and test skeins are always worth the extra few minutes.