[6] The flowers are 15–25 mm in diameter with five petals, which can be coloured white, blue, yellow, and red depending on the species.

[7] The soils most suitable for flax, besides the alluvial kind, are deep loams containing a large proportion of organic matter.

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.

Since then, flax has lost its importance as a commercial crop, due to the easy availability of more inexpensive synthetic fibres.

[22] 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.

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).

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.

As a result of alternating rain and the sun, an enzymatic action degrades the pectins which bind fibers to the straw.

Separating the usable flax fibers from other components requires pulling the stems through a hackle and/or beating the plants to break them.

The second part of the process brings the flax into a state for the very finest purposes, such as lace, cambric, damask, and very fine linen.

[26] Most types of these basic varieties have similar nutritional characteristics and equal numbers of short-chain omega-3 fatty acids.

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.

[31] 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.

[40] A third showed that consuming flax seed or its derivatives may reduce total and LDL-cholesterol in the blood, with greater benefits in women and people with high cholesterol.

[41] A fourth showed a small reduction in c-reactive protein (a marker of inflammation) only in persons with a body mass index greater than 30.

[46] Typical concentrations (for example, 0.48% in a sample of defatted dehusked flax seed meal) can be removed by special processing.

[25] The high omega-3 content also has a further disadvantage, because this fatty acid oxidises and goes rancid quickly, which shortens the storage time.

[27][49] 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[25] and cattle,[48] but cannot be digested by non-ruminants and can be detrimental to young animals, unless possibly treated with enzymes.

[51] 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 supplement to water buffaloes in India, and provided a better diet than forage alone, but not as good as when substituted with soy meal.

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.

[25] Raw, immature linseeds contain an amount of cyanogenic compounds and can be dangerous for monogastric animals, like horses and rabbits.

[25][51] 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.

[55] Flax mills for spinning flaxen yarn were invented by John Kendrew and Thomas Porthouse of Darlington, England, in 1787.

Pond-retted flax is traditionally considered of lower quality, possibly because the product can become dirty, and is easily over-retted, damaging the fiber.

This generally takes two or three weeks longer than pond retting, but the end product is less likely to be dirty, does not smell as bad, and because the water is cooler, is less likely to be over-retted.

This process normally takes a month or more, but is generally considered to provide the highest quality flax fibers, and it produces the least pollution.

A heckle is a bed of "nails"—sharp, long-tapered, tempered, polished steel pins driven into wooden blocks at regular spacing.

In September 2009, Canadian flax exports reportedly had been contaminated by a deregistered genetically modified cultivar called 'Triffid' that had food and feed safety approval in Canada and the U.S.[60][61] Canadian growers and the Flax Council of Canada raised concerns about the marketability of this cultivar in Europe where a zero tolerance policy exists regarding unapproved genetically modified organisms.