Carthamus (Safflower) in Zone 4a & 4b
Carthamus tinctorius
When to plant carthamus (safflower) in zone 4b
Zones 4a and 4b share the same average frost dates in our data, so this page covers both.
Method: Either: Start indoors for an earlier harvest, or direct-sow outside for less fuss. Carthamus (Safflower) tolerates either.
| Start indoors | Apr 17–Apr 24 |
|---|---|
| Direct sow / transplant outside | May 15–May 22 |
| Estimated bloom | Aug 13–Aug 20 (~90 days after planting) |
Spacing: 4 per square foot (square-foot-gardening spacing). Mature height: 1.5-2 ft.
Carthamus, better known as safflower, is a thistle-like cut flower historically grown as an oilseed and dye crop, with bright orange-yellow blooms that hold their color well once dried.
How carthamus (safflower) fits zone 4's season
Zone 4b's frost-free window runs about 128 days, from May 15 to September 20. Carthamus (Safflower) needs about 90 days from sowing to first harvest.
Good companions
No standout companions recorded yet for Carthamus (Safflower).
Where to buy carthamus seeds
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See it growing
Search YouTube for "growing carthamus (safflower)" videos → (a live search, not a hand-picked video; results vary and aren't vetted by us)
← Back to the full zone 4b calendar · Full companion planting guide · Full plant profile · Plan your beds in the Garden Designer →
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Growing Carthamus (Safflower) in USDA zone 4b: when to start seeds indoors, when to direct-sow, and when to expect a bloom.
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