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COG Organic Field Crop Handbook


3.5 Flax

Flax, Linum usitatissimum is a slender erect annual, 45-90cm tall with blue or sometimes white, pink or violet flowers. The flowers open shortly after sunrise and the petals drop before noon. Flowering starts after 45-60 days and continues for about three weeks. The seeds take another 30-40 days to mature. Available varieties mature in the 90-100 day range. In thick stands only the maistem develops but in thin stands four or more tillers may be produced.

Flax is grown mainly for the oil extrated from the seed - lineseed oil. The remaining linseeed meal averages 35% protein and is used asa a livestock suppliment. The majority of flax grown is grown in western Canada but it can be grown in Ontario and Quebec. Canadian flaxseed is higher in quality than any other on the world market. Organic farmers grow flax seed for human consumption -

¥Reasons for Crop selection

Flax brings diversity to a crop rotation. It is suitable in rotation with wheat and other small grains. The method of crop production and equipment for sowing and harvesting are the same but because it is from a different plant group it is not affected by diseases and pests that affect cereals.

It is non competitive with weeds but this characteristic makes it a good companian crop for clover an alfalfa. The small leaves fall fradually when ripening allowing an increasing amount of light to reach the underseeded crop.

Flax should not be grown in areas subject to soil drifting unless it is underseeded with a cover crop.

¥Crop requirements

Flax is a cool season crop best grown in areas with less than 2700 heat units. It is adapted to well drained loams, silt loams, and clay loams. It has a relatively short tap root with fibrous barnches that grow as deep as 1.2m into light soil but yields are reduced on droughty soils when temperatures are high at grain filling. Spring and early fall frosts rarely damge flax and after the plants have ppassed the two leaf stage they can withstand temperatures as low as -8oC for a short time.

Flax is considered a light feeder for placing it in the rotation. It is less demanding of nutrients (nitrogen, phosphorus, potassium and sulphur) than wheat, oats or barley however some farmers consider it similar to oats.

A 20bu/ac crop will remove:

N - 54lbs, p - 22lbs, P-45lbs

Varieties should be chosen for oil quality and yield, disease (rust) resistance and whether early or late maturing.

¥Planting methods

For highest yields and best weed control spring planting when the soil is moderately warm (that is late April to the second week of May depending on region) is recommended. Seeding can be delayed to control early germinating weeds such as wild oats.

A moist, firm and weed free seedbed is needed. If there is likely to be a problem with early weeds promote germination with tillage not more than 10cm deep. The weeds are then killed with subsequent tillage shallower than the first to avoid bringing up more weed seeds. Seed immediately afterwards. If deep tillage is necessary packing may be required.

Seeding rates:

Prairies 31-45kg/ha., 28-40lb/ac.

Eastern Canada 40-45kg/ha , 35-40lb/ac

The higher rates should be used only where there is enough moisture available to suport the crop.

On the prairies flax often follows wheat and can be underseeded with sweet clover. In eastern Canada flax may replace or preceed barley in the rotation. uality and yield, disease Tillage requirements will depend on the soil and whether or not a winterkilled cover crop was used the previous fall.


Emergence will also be hindered if crusting occurs after a heavy rain, this should not be a problem in soils wilh good levels of organic matter but if it occurs harrowing may be necessary.

Test weight for flax is ? kg/hl or ?lb/bu

¥ Crop Management

Flax has a more open canopy than cereals and does not compete well with weeds, therefore it is advisable to plant flax in a clean field. Underseeding clover or other forage crops is probably the most effective weed control stategy. Clover seed can be broadcast after the flax is up and harrowed in.

Disease is controlled by rotation design - do not follow lentils or peas because of Rhizoctonia and have at least three years between crops. Rust resistant varieties are available.


In Ontario swathing flax followed by combining produces drier seed. This is done when the seeds have turned dark brown and 90%c of the leaves have fallen off. Leave a high stubble to hold the windrows off the ground to facilitate drying. Under good conditions the crop can be combined 3-4 days after swathing. When combining close up the clearance between the cylinders and convave to about half that of grain and slow down the cylinder to avoid damaging the seed coat which is easily broken if the seed is very dry.

Yields on organic farms are comparable to conventional.

Flax straw should be chopped and spread if not baled for straw. It decomposes slowly in the soil.

Suitable following crops:

Flax is often followed by a stand of clover or ? (check Hack farm notes.)

"Harvesting is fairly critical with flax. If you don't get the timing right, it will spoil very easy when its ripe. It has to be cut with a swther and it's fairly tough to cut. Then after about 3 to 4 days of good sunshine we like to combine it before we get a rain."


Copyright © 1992 Canadian Organic Growers. Inc

Reprinted with permission. All rights reserved.


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