Growing Carthamus (Safflower): A Complete Profile
By Growing Home Greens Team · August 10, 2026
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.
Sowing
Direct-seeding is recommended, done after the last frost with the seed covered lightly; seedlings develop best at 65°F after germination. Transplanting also works, started 4 to 5 weeks before planting out. Germination takes 10 to 14 days at 68-72°F. Space plants 6 to 9 inches apart.
Cut at the right moment
Fresh-cut harvest timing matters more than usual here: cut stems once flowers have begun to open and show color, since stems cut before any color shows won’t continue opening once in a vase, unlike a lot of cut flowers that finish opening after cutting. For dried arrangements, wait until flowers are fully open before air drying.
Heat tolerance has limits
Despite its thistle-like, tough appearance, safflower handles intense heat less well than expected. Southern growers should provide roughly 30 percent shade or some afternoon shade to keep plants performing well through summer.
Carthamus has no recorded companions or antagonists in our data. See the full companion guide for carthamus for how it’s tracked. At 4 plants per square foot, it’s a good addition to a dried-flower row in the Garden Designer, with afternoon shade planned in for hot-summer regions.
Source: Carthamus (Safflower): Key Growing Information, Johnny’s Selected Seeds.
Companion planting guide for Carthamus (Safflower) · Find your planting dates
Typically viable in USDA zones 2-11. Not sure your zone? Look it up by ZIP code.
Method: Either: Start indoors for an earlier harvest, or direct-sow outside for less fuss. Carthamus (Safflower) tolerates either.
See exact start-indoors, direct-sow, and harvest dates for your zone →
How many Carthamus (Safflower) plants fit per square foot?
Spacing: 4 per square foot (square-foot-gardening spacing). Mature height: 1.5-2 ft.
Varieties worth considering
- 'Zanzibar' carthamus: Johnny's Selected Seeds describes this as a sturdy, versatile option for both flowers and foliage, one of their standard carthamus offerings for cut-flower growing. (source)
Cited from the source shown next to each variety. We haven't grown these ourselves yet, so treat this as a research-backed starting point, not a personal endorsement.
Where to buy carthamus seeds
As an Amazon Associate we earn from qualifying purchases. Some links on this page also go to other retailers we may earn a commission from as an affiliate, at no extra cost to you. We only recommend products with a genuine consensus of positive, independent reviews. See the sources cited on each item.
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)
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Growing Carthamus (Safflower): A thistle-like cut flower historically grown as an oilseed and dye crop, whose bright orange-yellow blooms hold their color well dried.
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