Carthamus (Safflower) in Zone 5a & 5b
Carthamus tinctorius
When to plant carthamus (safflower) in zone 5b
Zones 5a and 5b 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 12–Apr 19 |
|---|---|
| Direct sow / transplant outside | May 10–May 17 |
| Estimated bloom | Aug 8–Aug 15 (~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 5's season
Zone 5b's frost-free window runs about 148 days, from May 10 to October 5. 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 5b 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 5b: when to start seeds indoors, when to direct-sow, and when to expect a bloom.
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