Flax Plant Profile

Blue Flax Flowers (Linum usitatissimum) in a field in Canada

Lijuan Guo Photography / Getty Images

Native to Central Asia and the Mediterranean region, flax plants were originally cultivated in Mesopotamia, Assyria, and Egypt for over 5,000 years. Flax (Linum usitatissimum) was one of the first crops domesticated by humankind, originally used for fiber. Only when the cotton gin was invented did flax production start to decrease. Now, we are experiencing a resurgence in planting this annual herb and a renewed appreciation for its wild beauty and practical uses of the plant's fiber, oil, and seeds.

While the average gardener may not be able to process linen or the plant's linseed oil, it has become quite a popular hobby to harvest flaxseed.

In addition to such versatile nature, the rather tough plant adds a certain whimsy to any wildflower garden and it is easy to grow. This erect annual herb grows three to four feet tall, donning numerous flat gray-green leaves. Small five-sepal flowers are born in sky blue (and occasionally white or pale pink in some other varieties). Within each five-celled fruit capsule are up to 10 seeds in yellow, light brown, or dark brown. Learn how to sow the seeds and care for the plants consistently to stretch the harvest from summer through autumn.

Botanical Name Linum usitatissimum
Common Names Flax plant, flax, common flax, linseed
Plant Type Annual herb
Mature Size Three feet tall
Sun Exposure Full sun
Soil Type Rich, sandy or loamy, well-drained
Soil pH 5-7
Bloom Time Mid-spring through summer
Flower Color Blue, white, pale pink
Hardiness Zones 5, 6, 7, 8, 9
Native Area Central Asia and the Mediterranean region
Blue Flax Flowers (Linum usitatissimum) in a field in Canada
Lijuan Guo Photography / Getty Images

How to Grow Flax Plants

There are more than 300 flax cultivars. Choose one that would fulfill the desired primary use. Shorter branching varieties are best for seed production. Long-stemmed, sparsely branched varieties are naturally better for fiber production.

Akin to its wildflower cousins blue flax and scarlet flax, the common flax is a cool season plant. Seeds can also be started indoors six to eight weeks before last frost. Because flax roots are sensitive, you should transplant seedlings into larger containers to avoid them becoming root-bound.

To encourage fast, undisturbed root growth, direct sowing is recommended. Plant seeds when the ground can be worked in early spring. Seedlings that have at least two leaves can survive a late frost at temperatures as low as 28 degrees Fahrenheit.

Light

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

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.

Water

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, too 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.

Pests

Flax tolerates "disease, drought, fungi, grazing, herbicides, hydrogen fluoride, high pH, pesticides, rust, virus and weeds" (according to Purdue University Center for New Crops & Plants Products which cites the Central Asian, Near Eastern and Mediterranean Centers of Diversity).

Harvesting Seed and Fiber

After planting flax in early spring, it can also be sown in late summer and early fall in milder climates where there are little to no extremes of snow and rain.

Most flax will mature in 90 to 120 days. Harvest seeds by uprooting the entire plant. Tie together the stems and hang them to dry for three to five weeks until the seed heads completely dry out. Essentially, flaxseed is harvested in the same way as wheat. Consider using a grain binder with a swather (windrower).

Fiber flax in particular prefers abundantly moist (but not soggy) soil and cool temperatures during the growing season, then warm dry conditions during the harvest of seed and fiber. There are two means of harvesting fiber: dew retting and water retting.

Dew retting takes a few weeks. Spread the plant on the grass and let the dew or rain moisten it. If there is not enough natural moisture occurring at that time, gently add with a hose or watering can.

Water retting can be done quicker. Soak flax in water, perhaps a stream or river. Dig a small pond or hole to flood with water (or find a container to fill). Using water that is warmed at about 95 degrees Fahrenheit will accelerate the water retting period to 100 hours. Note: There will be an unpleasant stench during this process.

Propagation

While flax can be propagated from stem cuttings, the more common method is by seed. When 90 percent of the seed capsules (bolls) have turned brown, that is a sign that the plant is fully mature. Be aware that static electricity may occur at temperatures near 100 degrees Fahrenheit or low humidity levels, causing seeds to cling together. In this event, wait until a cooler day or more humid day to harvest or propagate.

Carefully remove each seed (thresh) to reduce the risk of cracking. Best seeds for propagation or consumption will be nice and plump, not wilted or diseased. Store seeds at low consistent moisture between eight and 10 percent.

Medicinal Purposes and Toxicity Concerns

Both linseed oil and flaxseed can be mixed in with dog food for added nutrition. Ground flaxseed offers dietary fiber for intestinal health and reduced constipation for dogs and occasionally for cats. Omega-3 fatty acids boost the immune system and omega-6 adds shine to their coats. Though some professionals caution that not all animals can process such products effectively or safely. (Wag Walking suggests raw unprocessed flaxseed can be most toxic and contact with the plant can cause skin irritation.)

The Linum plant genus is "considered anodyne, astringent, cyanogenic, demulcent, diuretic, emollient, expectorant, laxative, suppurative, and vulnerary," according to Purdue University, which explores how flax and other members of the genus find their way into "folk remedies for boils, bronchitis, burns, cancer, carbuncles, cold, conjunctivitis, corns, coughs, diarrhea, gonorrhea, gout, inflammation, intoxication, labor, rheumatism, scalds, sclerosis, sores, spasms, swellings, tumor."

Linseed tea has been used to treat colds, coughs and urinary tract issues. Linseed oil also can be taken as a laxative; and applied with equal amounts of lime water can ease burns. With honey, it is beloved as a natural cosmetic for removing facial spots. All around, the common flax plant is incredibly versatile. Welcome the delicate flowers of this tall fibrous herb to your garden, and find countless opportunities to experiment and watch this plant quickly transform itself and your life.