Bachelor's Button (Cornflower) in Zone 10a & 10b
Centaurea cyanus
Yes, bachelor's button (cornflower) grows in zones 10a and 10b. Plant it outside in Sep–Nov. For a fall crop, plant out in Sep–Nov.
When to plant bachelor's button (cornflower) in zone 10b
Zones 10a and 10b share the same average frost dates, so this page covers both.
Method: Either: Start indoors for an earlier harvest, or direct-sow outside for less fuss. Either works.
| Window | Fall window |
|---|---|
| Start indoors | Not typically started indoors |
| Direct sow / transplant outside | Sep–Nov |
| Estimated bloom | ~75 days after planting |
Spacing: 3 per square foot (square-foot-gardening spacing). Mature height: 1-3 ft.
Zone 10b dates sourced from growinginthegarden.com.
Fall window: the last sowing date is the average first frost minus days to maturity, the method in Purdue Extension's fall garden guide, which lists bachelor's button (cornflower) for late-summer planting.
Plant alongside it in zone 10b
These go outside within two weeks of bachelor's button (cornflower) in zone 10b, so one planting day can cover them.
- CalendulaSep–Nov
- DelphiniumSep–Nov
- Gaillardia (Blanket Flower)Sep–Nov
- LarkspurSep–Jan
- PetuniaSep–Mar
- SnapdragonSep–Feb
Bachelor's button (also sold as cornflower) is about as low-effort as annual flowers get. It tolerates cold better than most, fills in fast, and doesn't ask for much once it's in the ground. Wiry 1- to 3-foot stems carry small, fringed, frilly round blooms, most often blue, though pink, white, and maroon show up in mixes too.
How bachelor's button (cornflower) fits zone 10's season
Zone 10b's frost-free window runs about 324 days, from January 30 to December 20. Bachelor's button (cornflower) needs about 75 days from sowing to first bloom.
Bachelor's Button (Cornflower) planting windows in every zone
Zone 10b is highlighted. Useful for comparing against a neighbouring zone, or for a garden somewhere else.
| Zone | Start indoors | Sow or plant out | Bloom |
|---|---|---|---|
| 2a & 2b | Apr 1–Apr 8 | May 6–May 13 | Jul 20–Jul 27 |
| 3a & 3b | Apr 11–Apr 18 | May 16–May 23 | Jul 30–Aug 6 |
| 4a & 4b | Mar 27–Apr 3 | May 1–May 8 | Jul 15–Jul 22 |
| 5a & 5b | Mar 22–Mar 29 | Apr 26–May 3 | Jul 10–Jul 17 |
| 6a & 6b | Mar 7–Mar 14 | Apr 11–Apr 18 | Jun 25–Jul 2 |
| 7a & 7b | Feb 20–Feb 27 | Mar 27–Apr 3 | Jun 10–Jun 17 |
| 8a & 8b | Feb 4–Feb 11 | Mar 11–Mar 18 | May 25–Jun 1 |
| 9a & 9b | Dec 28–Jan 4 | Feb 1–Feb 8 | Apr 17–Apr 24 |
| 10a & 10bFall window (your zone) | Not usually | Sep–Nov | ~75 days after planting |
| 11a & 11b | Nov 13–Nov 20 | Dec 18–Dec 25 | Mar 3–Mar 10 |
Bloom dates are about 75 days after the sow or plant-out date, not after starting seeds indoors.
Zone 2 sows before zone 3 here, which looks wrong and is not. USDA zones rank winter cold, not season length, and zone 2 is mostly interior Alaska, where hard winters come with warm summers. More on what a zone measures.
Good companions
No well-established companions for bachelor's button (cornflower).
Where to buy bachelor's button seeds
Botanical Interests · True Leaf Market · High Mowing Organic Seeds (each supplier's bachelor's button seeds)
See why we recommend these suppliers →
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See it growing
Search YouTube for "growing bachelor's button (cornflower)" videos → (a live search, not a hand-picked video; results vary and aren't vetted by us)
← Back to the full zone 10b calendar · Plan your beds in the Garden Designer →
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Growing Bachelor's Button (Cornflower) in USDA zone 10b: when to start seeds indoors, when to direct-sow, and when to expect a bloom.
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