Why Your Flax Needs to Ret

You've pulled your flax, rippled off the seed heads (or saved them for next year's sowing), and now you have an armful of straw that looks nothing like the golden fibre in your imagination. Before those stalks can become spinnable linen, the pectins — the natural glues binding the bast fibres to the woody core — have to break down. That's retting. Skip it and you'll be fighting the shives for hours with a knife; do it well and the fibres almost fall free.

Retting is really controlled rotting, and it pays to think of it that way. You're inviting bacteria and fungi to do a specific job for you, then stopping them at exactly the right moment.

Water Retting versus Dew Retting

There are two broad routes, and the right one depends on your weather, your space, and how much of your summer you want to spend sniffing a bucket.

• Water retting is faster — often five to fourteen days — and gives a cleaner, more uniform fibre. It needs a trough, a water butt, or a tub, and it smells like a pond in August. Warm, soft water speeds things up; hard mains water slows the bacteria down.
• Dew retting is the traditional field method: spread the straw on grass and let dew, rain and soil fungi work on it over three to six weeks. It needs almost no equipment, but it's weather-dependent, and the fibre tends to come out a little darker and coarser.

In a British summer you can usually do either. A damp, mild July favours water retting; a showery but breezy spell is ideal for dew retting.

Water Retting Step by Step

Bundle your stalks into loose sheaves about the thickness of your wrist and tie them with twine — not too tight, because the water needs to circulate. Stand them upright in a tub or trough, or lay them flat in a water butt, then weigh them down with a brick or a couple of clean stones. Keep the stalks fully submerged; any part poking above the surface will rot unevenly and grow mould.

Rainwater is far better than tap water, so a water butt is your friend here. If you're using a trough or an old bath, top it up with rainwater saved in a barrel. Change roughly half the water every few days if the smell becomes truly fearsome, but don't be too tidy — you're cultivating bacteria, not sterilising a hospital ward.

Check daily from day five onwards. The water will darken and the stalks will soften. Lift a bundle and squeeze a stalk between finger and thumb: when the fibres slide away from the core with gentle pressure, you're very close.

Dew Retting in a Small Garden

If a water butt full of pong isn't your style, dew retting is far gentler on the nose and on the neighbours. Find a patch of long grass, a lawn edge, or even a flat shed roof, and lay the stalks in a single loose layer — no thick mats, or the middle will never see any dew. Turn the straw every few days with a fork, and bring it under cover if a proper heatwave is forecast, since baking sun makes the fibres brittle.

Slugs, snails and the occasional mouse will investigate. A light scattering of straw over the top helps, and so does keeping the layer thin. Three to six weeks is typical in the UK, depending on how much moisture the grass holds and how often the dew settles.

Knowing When to Stop

Under-retted and over-retted flax cause two different problems, and both are disappointing. Too little retting means the fibres cling to the woody core and you'll rip them apart during breaking. Too much means the fibres themselves weaken and turn to stringy mush.

The classic test is the snap test. Take a stalk and bend it sharply between your fingers. Properly retted straw snaps cleanly, the woody core breaks with a dry crack, and the fibres separate from it easily, almost like a loose sleeve. If the stalk bends like a green twig, it needs more time. If the fibres pull away in a slimy clump, you've gone too far — stop immediately and dry the rest.

Once you're happy, dry the stalks thoroughly before storing. Stand bundles upright in an airy shed, or lay them on racks in a dry, breezy spot out of direct sun. Damp flax goes mouldy fast, and mould ruins fibre. Once bone dry, it will keep for months until you're ready to break, scutch and hackle.

A final tip: do a small test bundle first. Retting is far easier to judge on a handful of stalks than on your whole harvest, and a trial batch teaches you more in a fortnight than any book. Then, once your fibre is dry and gleaming, the real pleasure begins — spinning your own linen thread.