Herb to Know: Flax

By Rita Buchanan
Published on June 1, 1995
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After blooming, the seed pods swell and turn brown.
After blooming, the seed pods swell and turn brown.
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Petals unfold in the morning and drop by evening.
Petals unfold in the morning and drop by evening.
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Click on the IMAGE GALLERY for more images of flax.
Click on the IMAGE GALLERY for more images of flax.
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Flax seed has beneficial omega-3 fatty acids.
Flax seed has beneficial omega-3 fatty acids.

The life of a flax flower is transitory: a flower lasts less than one day. But each plant makes dozens of flowers for three to four weeks, and a plot of flax in bloom looks like a reflection of the sky. Then seedpods swell to the size of a pea and turn from green to gold as the seeds inside ripen, and the plants dry out and die.

The species of flax grown for fiber and seed production is an annual called Linum usitatissimum; that’s Latin for “the most useful kind of flax.” Flax is almost always grown like a grain crop, in plots of many plants crowded close together. Each individual plant makes one or more slender, erect stems about 3 feet tall, scattered with narrow, pale green leaves about 1 inch long. The stems branch near the top to bear blue or white round, 1/2-inch-wide flowers with five petals.

Different cultivars of flax have been selected for maximum yield and quality of either fiber or oil. Farmers specialize in one product or the other, choose cultivars accordingly, and take slightly different approaches to growing and harvesting their crops. On a backyard scale, it isn’t necessary to specialize. From a flax patch about 4 feet square, you can harvest enough fiber to make a basket and enough seeds for a batch of bread or crackers.

Grow and Harvest Flax

Flax tolerates a range of soils and climates and can be grown in almost any part of the United States. Choose a site in full sun, with deep, fertile, well-drained soil, and prepare it as you would for growing vegetables or flowers. Flax grows best in cool weather, so sow it outdoors as soon as you can work the soil in spring, at the same time that you would sow peas, lettuce or other cool-weather crops. This can be as early as January or as late as May, depending on where you live. 

Rake the surface of the soil to prepare a smooth, fine-textured seedbed. Measure your planned flax plot to determine its area, and plan to sow about one tablespoon of flax seeds per 10 square feet. Dust the small brown seeds with flour before sowing so that you can scatter them evenly across the surface of the plot. Then use a rake to draw the seeds down into the soil, covering them 1/4- to 1/2-inch-deep. Water gently if the soil starts to dry out before germination, which takes about 10 days.

Seedling flax plants quickly develop a good root system and need watering only if the weather is unusually warm, dry or windy. Pull out any weeds that appear before the seedlings have grown a few inches tall; after the seeds sprout, the flax plants will crowd out any weeds. Rabbits and rodents sometimes nibble flax, but it has few insect or disease problems. The only common, serious crisis in growing flax is that the tender stalks sometimes get knocked flat by hail or heavy rainstorms. If that happens, use the tines of a garden fork. They may straighten up again, or at least partially recover.

The fibers in the stem of the flax plant form a thin layer between the woody core and the outer skin or epidermis that runs all the way from the roots to the tips. The fibers have already reached their full length when the flax begins to flower, about two months after planting, but they are still thin, delicate and weak. From flowering until the death of the plant, the fibers become increasingly thicker and stronger, but also more stiff and brittle. Unfortunately, fiber quality peaks before the seeds have fully ripened. If you harvest the plants early enough (usually about three months after planting) to get top-quality fiber, you sacrifice most of the seed crop. If you wait until the seeds are ripe (about four months after planting), the fiber has become coarse. This difference in the timing of harvest is a major reason why commercial flax farmers produce either fiber or seeds but not both. Again, a hobby grower can compromise. The fiber from mature plants is too coarse for weaving fine fabrics, but it’s acceptable for making baskets or other simple craft projects.

To reap both seeds and fiber, harvest the flax about four months after planting. The leaves on the lower half or two-thirds of the stem will be turning yellow and dropping off. Most of the seedpods will have turned gold or tan; if you shake them, the seeds will rattle inside. Grasp the stems, a handful at a time, right at ground level and pull them up, roots and all. Shake the soil off the roots, lay a few handfuls of stems together side by side, and use rubber bands or string to secure them into a bundle.

Thresh Flax Seeds

Hang the bundles in a warm place with good air circulation. After a few weeks, when the stalks are stiff and dry, you can thresh out the seeds. This takes some effort: you have to crush open the pods. One method is to slide a pillowcase over the top end of a bundle, tie the case securely around the stems, then put it down on a paved driveway, sidewalk or other hard, flat surface. Beat the pods through the cloth with a block of wood, roll them with a rolling pin (push hard!), jump on the bag or drive back and forth over it with a car.

After several minutes of such activity, open the bag to confirm that most of the pods have been crushed, shake the bundle vigorously to knock out all the seeds, then pour the seeds and chaff out of the pillowcase into a bowl and start again with the next bundle. After threshing all the bundles, sift the seeds through a colander or coarse strainer to remove bits of stems and broken pods. Step outdoors in the breeze and pour the seeds slowly from one container to another to winnow away any remaining chaff or dust.

Process Flax Fibers

Processing the bundles of stems to extract the fibers for spinning is a complex task that requires simple but special tools, a lot of hard physical work, and a sense of timing and judgment that comes only from long experience. The first step, called retting, involves soaking or wetting the stems for a period of days or weeks to promote bacterial action, which separates the different layers of stem tissues and loosens the fibers. After retting, the stems are dried again, then crushed between the wooden blades of a tool called a break or brake, which breaks the woody core into short bits that fall away from the mass of fibers. Finally, the bundles are combed through metal-tined combs called hackles. The result: a smooth bundle of long, straight fibers called line flax and a pile of fluffy, tangled, shorter fibers called tow. The line flax is used to make crisp, glossy fabrics, and the tow is used for everyday goods. 


Rita Buchanan is a weaver, spinner, and gardener in Winsted, Connecticut. She is the author of A Dyer’s Garden, (Interweave Press, 1995).

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