Growing Scarlet Flax: A Complete Profile
By Growing Home Greens Team · August 20, 2026
Scarlet flax is a wispy annual whose individual flowers last a single day. The plant compensates by producing a great many of them.
Sow it thickly or not at all
A single scarlet flax plant looks like a weed with a red flower on it. Sown as a block it reads as a drift of colour, because the fine stems disappear at a distance and the flowers do not. Four to the square foot is the minimum that works.
It reaches 12 to 18 inches. NC State Extension does not publish a height for the species, so that figure comes from the seed trade rather than an extension service, which is worth knowing when you plan around it.
Full sun, poor soil, no fuss
Zones 4 through 9, full sun to partial shade, and it becomes strikingly drought tolerant once established. Rich soil makes it flop. Seed goes in about an eighth of an inch deep after the last frost.
Not the flax that makes linen
Linum grandiflorum is the ornamental. Linum usitatissimum is the fibre and linseed crop, taller, blue-flowered, and grown for entirely different reasons. The seed of the ornamental is not what you would use in the kitchen.
Source: NC State Extension Gardener Plant Toolbox, Linum grandiflorum.
Companion planting guide for Scarlet Flax · Find your planting dates
Typically viable in USDA zones 4-9. Not sure your zone? Look it up by ZIP code.
Mature height: 1-1.5 ft
Method: Direct sow: Direct-sow outside. It doesn't transplant well, or doesn't need the extra time indoors.
When to plant scarlet flax, by zone
Every zone scarlet flax grows in. Pick your zone in the header and it will be highlighted here. Each zone links to its full page.
| Zone | Start indoors | Sow or plant out | Bloom |
|---|---|---|---|
| 4a & 4b | Not usually | May 15–May 22 | Jul 24–Jul 31 |
| 5a & 5b | Not usually | May 10–May 17 | Jul 19–Jul 26 |
| 6a & 6b | Not usually | Apr 25–May 2 | Jul 4–Jul 11 |
| 7a & 7b | Not usually | Apr 10–Apr 17 | Jun 19–Jun 26 |
| 8a & 8b | Not usually | Mar 25–Apr 1 | Jun 3–Jun 10 |
| 9a & 9b | Not usually | Feb 15–Feb 22 | Apr 26–May 3 |
Bloom dates are about 70 days after the sow or plant-out date.
See exact start-indoors, direct-sow, and harvest dates for your zone →
How many Scarlet Flax plants fit per square foot?
Spacing: 4 per square foot (square-foot-gardening spacing). Mature height: 1-1.5 ft.
Where to buy scarlet flax seeds
Botanical Interests · True Leaf Market (scarlet flax seeds)
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See it growing
Search YouTube for "growing scarlet flax" videos → (a live search, not a hand-picked video; results vary and aren't vetted by us)
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Growing Scarlet Flax: Fine wiry stems and flowers that open in the morning and drop the same day, replaced the next.
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