Flax (Linum usitatissimum)

Flax (Linum usitatissimum) is a rather tough plant that adds a certain whimsy to any wildflower garden and it is easy to grow. This erect annual herb grows up to three feet tall, donning numerous flat gray-green leaves. Flax plants require full sun and slightly acidic soil. Learn how to sow the seeds and care for the plants consistently to stretch the harvest from summer through autumn.

I. Appearance and Characteristics 

Flax, also known as common flax or linseed, is a flowering plant, Linum usitatissimum, in the family Linaceae.

In addition to referring to the plant, the word “flax” may refer to the unspun fibers of the flax plant. The plant species is known only as a cultivated plant and appears to have been domesticated just once from the wild species Linum bienne, called pale flax. The plants called “flax” in New Zealand are, by contrast, members of the genus Phormium.

Several other species in the genus Linum are similar in appearance to L. usitatissimum, cultivated flax, including some that have similar blue flowers, and others with white, yellow, or red flowers. Some of these are perennial plants, unlike L. usitatissimum, which is an annual plant.

Cultivated flax plants grow to 1.2 m (3 ft 11 in) tall, with slender stems. The leaves are glaucous green, slender lanceolate, 20–40 mm long, and 3 mm broad.

The flowers are 15–25 mm in diameter with five petals, which can be colored white, blue, yellow, and red depending on the species. The fruit is a round, dry capsule 5–9 mm in diameter, containing several glossy brown seeds shaped like apple pips, 4–7 mm long.

The earliest evidence of humans using wild flax as a textile comes from the present-day Republic of Georgia, where spun, dyed, and knotted wild flax fibers found in Dzudzuana Cave date to the Upper Paleolithic, 30,000 years ago. Humans first domesticated flax in the Fertile Crescent region. Evidence exists of a domesticated oilseed flax with increased seed-size from Tell Ramad in Syria and flax fabric fragments from Çatalhöyük in Turkey by c. 9,000 years ago. Use of the crop steadily spread, reaching as far as Switzerland and Germany by 5,000 years ago. In China and India, domesticated flax was cultivated at least 5,000 years ago.

Flax was cultivated extensively in ancient Egypt, where the temple walls had paintings of flowering flax, and mummies were embalmed using linen. Egyptian priests wore only linen, as flax was considered a symbol of purity. Phoenicians traded Egyptian linen throughout the Mediterranean and the Romans used it for their sails. As the Roman Empire declined, so did flax production. But with laws designed to publicize the hygiene of linen textiles and the health of linseed oil, Charlemagne revived the crop in the eighth century CE. Eventually, Flanders became the major center of the European linen industry in the Middle Ages.

In North America, colonists introduced flax, and it flourished there, but by the early 20th century, cheap cotton and rising farm wages had caused production of flax to become concentrated in northern Russia, which came to provide 90% of the world’s output. Since then, flax has lost its importance as a commercial crop, due to the easy availability of more durable fibres.

II. How to Grow and Care

Sunlight

Select a location that gets full sun. Flax cannot grow in shade.

Temperature and Humidity

Flax grows best in a temperature range of 65 to 70 degrees Fahrenheit and a relative humidity of about 75%. This plant is frost tolerant.

Watering

Lightly rake the soil gently to bury seeds with a half-inch of soil. Tamp down the seeds to ensure they make direct contact with the soil. Finely spray with water thoroughly; this will provide proper moisture while not drowning the seeds. Continue to water regularly. Seeds will germinate in about 10 days.

As plants mature, dry conditions may cause them to become short and woody. Maintain generous moisture without drenching or waterlogging. Put a thin layer of mulch to control moisture and weeds. Avoid planting in regions where there are heavy storms and high winds, and keep away from salt spray.

Soil

Flax plants prefer slightly acidic to neutral soil that is fertile and well-drained. Sandy or loamy soil is best. If soil is poor, prepare the site by mixing in a lot of organic matter such as compost or manure.

Plants thrive close together. Sprinkle one tablespoon of seed per 10 square feet to welcome about 40 plants per square foot. Given that the seeds are very small, dust them with flour so that they will scatter more evenly.

Fertilizing

Flax plants are sensitive to fertilizer and using it can injure seedlings. The plants usually don’t require fertilizing.

Propagation

While flax can be propagated from stem cuttings, since this is an annual, gardeners are unlikely to bother propagating and instead would grow from seed.

How to Grow From Seed

Seeds can be started indoors six to eight weeks before the last frost. Because flax roots are sensitive, you should transplant seedlings into larger containers to avoid them becoming root-bound. If you are taking seeds from a flax plant, the best seeds will be nice and plump, not wilted or diseased. Here’s how to grow flax plant from seed:

• Look for a sunny location, as flax cannot be grown in shade.
• If taking seeds from a flax plant, wait until 90 percent of the seed capsules (bolls) have turned brown. That is a sign that the plant is fully mature and ready to collect the seeds.
• Carefully remove each seed (thresh) to reduce the risk of cracking. Store seeds at low consistent moisture between eight and 10 percent until ready to plant.
• Add a mix of compost or organic matter if soil quality is poor.
• After smoothing the planting area, add 1 tbsp of seeds for every 10 sq. ft.
• Cover with 1/2 in. of soil.
• Keep soil moist but not drenched. Look for germination in about 10 days.

Potting and Repotting 

Flax plants can be grown in containers and they do well being crowded. Make sure to choose a container that has plenty of drainage holes and fill it 1/3 way up with potting mix (do not use fertilizer when grown in a container). Opt for shorter varieties of flax plant when growing in containers, between 12 to 36 inches tall.

Overwintering

Flax plants are frost tolerant. This is a cool-season annual plant that does not require overwintering in cold hardiness zones.

Pests and Diseases

Flax plants are prone to pests like flax bollworms, grasshoppers, cutworms, and potato aphids. While the latter three are general pests, the flax bollworm is the only one unique to the flax plant. Make sure to examine your plants regularly for signs of pests as they can cause damage if left untreated. Spraying is usually advised if an infestation is discovered.

III. Uses and Benefits 

• Culinary uses

A 100-gram portion of ground flax seed supplies about 2,234 kilojoules (534 kilocalories) of food energy, 41 g of fat, 28 g of fiber, and 20 g of protein. Whole flax seeds are chemically stable, but ground flax seed meal, because of oxidation, may go rancid when left exposed to air at room temperature in as little as a week. Refrigeration and storage in sealed containers will keep ground flax seed meal for a longer period before it turns rancid. Under conditions similar to those found in commercial bakeries, trained sensory panelists could not detect differences between bread made with freshly ground flax seed and bread made with flax seed that had been milled four months earlier and stored at room temperature. If packed immediately without exposure to air and light, milled flax seed is stable against excessive oxidation when stored for nine months at room temperature, and under warehouse conditions, for 20 months at ambient temperatures.

Three phenolic glycosides—secoisolariciresinol diglucoside, p-coumaric acid glucoside, and ferulic acid glucoside—are present in commercial breads containing flax seed.

• Fodder

After crushing the seeds to extract linseed oil, the resultant linseed meal is a protein-rich feed for ruminants, rabbits, and fish. It is also often used as feed for swine and poultry, and has also been used in horse concentrate and dog food. The high omega-3 fatty acid (ALA) content of linseed meal “softens” milk, eggs, and meat, which means it causes a higher unsaturated fat content and thus lowers its storage time. The high omega-3 content also has a further disadvantage, because this fatty acid oxidizes and goes rancid quickly, which shortens the storage time. Linola was developed in Australia and introduced in the 1990s with less omega-3, specifically to serve as fodder.

Another disadvantage of the meal and seed is that it contains a vitamin B6 (pyridoxine) antagonist, and may require this vitamin be supplemented, especially in chickens, and furthermore linseeds contain 2–7% of mucilage (fibre), which may be beneficial in humans and cattle, but cannot be digested by non-ruminants and can be detrimental to young animals, unless possibly treated with enzymes.

Linseed meal is added to cattle feed as a protein supplement. It can only be added at low percentages due to the high fat content, which is unhealthy for ruminants. Compared to oilseed meal from crucifers it measures as having lower nutrient values, however, good results are obtained in cattle, perhaps due to the mucilage, which may aid in slowing digestion and thus allowing more time to absorb nutrients.

One study found that feeding flax seeds may increase omega-3 content in beef, while another found no differences. It might also act as a substitute for tallow in increasing marbling. In the US, flax-based feed for ruminants is often somewhat more expensive than other feeds on a nutrient basis. Sheep feeding on low quality forage are able to eat a large amount of linseed meal, up to 40% in one test, with positive consequences. It has been fed as a supplement to water buffaloes in India, and provided a better diet than forage alone, but not as good as when substituted with soy meal. It is considered an inferior protein supplement for swine because of its fibre, the vitamin antagonist, the high omega-3 content and its low lysine content, and can only be used in small amounts in the feed.

Although it may increase the omega-3 content in eggs and meat, it is also an inferior and potentially toxic feed for poultry, although it can be used in small amounts. The meal is an adequate and traditional source of protein for rabbits at 8–10%. Its use in fish feeds is limited.

Raw, immature linseeds contain an amount of cyanogenic compounds and can be dangerous for monogastric animals, like horses and rabbits. Boiling removes the danger. This is not an issue in meal cake due to the processing temperature during oil extraction.

Flax straw left over from the harvesting of oilseed is not very nutritious; it is tough and indigestible, and is not recommended to use as ruminant fodder, although it may be used as bedding or baled as windbreaks.

• Flax fibers

Flax fiber is extracted from the bast beneath the surface of the stem of the flax plant. Flax fiber is soft, lustrous, and flexible; bundles of fiber have the appearance of blonde hair, hence the description “flaxen” hair. It is stronger than cotton fiber, but less elastic.

The use of flax fibers dates back tens of millennia; linen, a refined textile made from flax fibers, was worn widely by Sumerian priests more than 4,000 years ago. Industrial-scale flax fiber processing existed in antiquity. A Bronze Age factory dedicated to flax processing was discovered in Euonymeia, Greece.

The best grades are used for fabrics such as damasks, lace, and sheeting. Coarser grades are used for the manufacturing of twine and rope, and historically, for canvas and webbing equipment. Flax fiber is a raw material used in the high-quality paper industry for the use of printed banknotes, laboratory paper (blotting and filter), rolling paper for cigarettes, and tea bags.

Flax mills for spinning flaxen yarn were invented by John Kendrew and Thomas Porthouse of Darlington, England, in 1787. New methods of processing flax have led to renewed interest in the use of flax as an industrial fiber.

IV. Harvesting and Storage

Maturation

Flax is harvested for fiber production after about 100 days, or a month after the plants flower and two weeks after the seed capsules form. The bases of the plants begin to turn yellow. If the plants are still green, the seed will not be useful, and the fiber will be underdeveloped. The fiber degrades once the plants turn brown.

Flax grown for seed is allowed to mature until the seed capsules are yellow and just starting to split; it is then harvested in various ways. A combine harvester may either cut only the heads of the plants, or the whole plant. These are then dried to extract the seed. The amount of weeds in the straw affects its marketability, and this, coupled with market prices, determines whether the farmer chooses to harvest the flax straw. If the flax straw is not harvested, typically, it is burned, since the stalks are quite tough and decompose slowly (i.e., not in a single season). Formed into windrows from the harvesting process, the straw often clogs up tillage and planting equipment. Flax straw that is not of sufficient quality for fiber uses can be baled to build shelters for farm animals, or sold as biofuel, or removed from the field in the spring.

Two ways are used to harvest flax fiber, one involving mechanized equipment (combines), and a second method, more manual and targeting maximum fiber length.

Harvesting for fiber

• Mechanical

Flax for fiber production is usually harvested by a specialized flax harvester. Usually built on the same machine base as a combine, but instead of the cutting head it has a flax puller. The flax plant is turned over and is gripped by rubber belts roughly 20–25 cm (8–10 inches) above ground, to avoid getting grasses and weeds in the flax. The rubber belts then pull the whole plant out of the ground with the roots so the whole length of the plant fiber can be used. The plants then pass over the machine and is placed on the field crosswise to the harvester’s direction of travel. The plants are left in the field for field retting.

The mature plant can also be cut with mowing equipment, similar to hay harvesting, and raked into windrows. When dried sufficiently, a combine then harvests the seeds similar to wheat or oat harvesting.

• Manual

The plant is pulled up with the roots (not cut), so as to increase the fiber length. After this, the flax is allowed to dry, the seeds are removed, and it is then retted. Dependent upon climatic conditions, characteristics of the sown flax and fields, the flax remains on the ground between two weeks and two months for retting. As a result of alternating rain and the sun, an enzymatic action degrades the pectins which bind fibers to the straw. The farmers turn over the straw during retting to evenly rett the stalks. When the straw is retted and sufficiently dry, it is rolled up. It is then stored by farmers before extracting the fibers.