Why Grow Flax for Both Seed and Fibre

Flax, Linum usitatissimum, is one of the few crops that will give you two harvests from the same patch: long golden fibre from the stems and oil-rich seed from the bolls. The catch is that the two aims pull in opposite directions. Fibre flax is bred tall and single-stemmed, sown thickly so it grows like a forest of straight wands. Linseed types are shorter, branch freely, and pour their energy into seed. A genuinely dual-purpose crop is a compromise, not a perfect marriage.

That said, a small plot can do it well. Grow a tall fibre type or a genuine dual-purpose variety rather than a dwarf linseed, and accept that your fibre will be a little coarser and your seed yield a little lower than a dedicated crop. The reward is a satisfying, old-fashioned sort of gardening: sowing a fine blue-flowered field, pulling it by hand, and following the whole process from retting to spinning.

Preparing the Ground: Fine Tilth and a Firm Bed

Flax has a shallow, delicate root system and hates a cloddy seedbed. It wants a fine, firm tilth that keeps moisture near the surface. Work the ground to a crumb in early spring, then let it settle.

• Soil: a fertile loam with a pH of 6–7 is ideal. Sandy loams warm quickly, which suits flax.
• Fertility: compost or well-rotted manure dug in the previous autumn is perfect. Avoid fresh manure or a nitrogen-rich feed just before sowing — lush growth lodges, and lodged stems make poor fibre.
• Stale seedbed: prepare the bed two or three weeks before sowing, let the weeds germinate, then lightly hoe them off. This knocks back the weed pressure that flax cannot outgrow.
• Rotation: never follow flax with flax. Leave at least five or six years before returning to the same ground, or you risk flax wilt building up in the soil.

Sowing at the Right Density

Timing matters. Sow from late March to mid-April, once the soil has reached about 7–8°C. Flax germinates in seven to fourteen days and puts on a growth spurt in early summer; a late sowing will flower in the heat and produce short, branchy stems.

Sow direct — flax resents transplanting — at 1–1.5cm deep. You can broadcast and rake in, but rows 15cm apart make weeding far easier. Then comes the crucial part: density. Fibre flax is sown thickly, at roughly 1,200–1,500 seeds per square metre, so the plants compete, grow tall, and throw no side branches. For a ten-square-metre bed, that is a scant 60–70g of seed.

For a dual-purpose patch, aim at the lower end of that range. Slightly thinner sowing gives more room for bolls to fill, while still keeping the stems tall enough to be worth processing. Firm the soil afterwards with a roll or by treading gently; good seed-to-soil contact is worth more than any fancy technique.

Weeding Without Harming the Stems

Flax seedlings are slow and slender, and that is exactly when weeds will bury them. The dense sowing does much of the work for you, but you will still need to intervene — carefully.

• Weed by hand, on your knees, while the plants are under 15cm tall. After that, stems bruise, kink, and never straighten, and a kinked stem is useless fibre.
• Work between the rows with fingertips only. No hoe, no trowel, no dutch hoe dragged anywhere near the stems.
• Do one pass when seedlings are 5–10cm high, and a second just before the stems shoot upwards in early summer. After that, leave it alone.
• Water the bed the day before weeding if the ground is dry, so delicate roots come away cleanly and the weeds pull easily.

Watch for flea beetle on young seedlings, which can riddle the leaves with small shot-holes. A thick sowing usually shrugs it off, and the plants grow away from the damage within a fortnight.

Judging the Harvest

For pure fibre, flax is pulled when the lower two-thirds of the stem has turned yellow and the bolls are still greenish — around 100 days from sowing, usually late July or August. For pure seed, you wait two or three weeks longer, until the bolls rattle, but by then the fibre has coarsened considerably.

For a dual-purpose crop, split the difference. Pull when the bottom third of the stem is yellow and the lowest bolls are beginning to brown; the seed will finish ripening in the sheaf. Pull, do not cut. The fibre runs down into the roots, and cutting throws away the longest, finest part of the staple. Grip low, pull firmly, and shake the soil from the roots.

Tie the stems into small sheaves about 20cm across, stand them in stooks to dry, then ripple off the bolls by pulling the heads through a coarse comb or a row of nails. Dry the seed somewhere airy and store it in paper.

Retting, Dressing and Realistic Yields

The stems now need retting — the controlled rotting that separates fibre from the woody core. Dew retting suits a British climate: lay the sheaves thinly on grass, turn them every few days, and check from about two weeks on. The fibre is ready when it peels away from the stem core in long strands with a gentle tug. Do not over-ret it, or the fibre weakens.

After that comes drying, breaking, scutching and hackling — several hours of work for a modest bundle. Be realistic about the numbers. A square metre of decent flax yields roughly half a kilogram of dried straw, and hand-processing might give you 40–80g of usable fibre. That is enough for a small skein or two, and worth every minute if you enjoy the craft. Grow it for the pleasure, the seed, and the line of blue flowers in June.