Sweet William in Zone 9a & 9b
Dianthus barbatus
Yes, sweet William grows in zones 9a and 9b. Start seeds indoors Dec 28–Jan 4 and plant out Feb 8–Feb 15.
When to plant sweet William in zone 9b
Zones 9a and 9b share the same average frost dates, so this page covers both.
Method: Start indoors: Start indoors from seed, then transplant outside. It needs a head start most zones can't give it by direct-sowing alone.
| Start indoors | Dec 28–Jan 4 |
|---|---|
| Direct sow / transplant outside | Feb 8–Feb 15 |
| Estimated bloom | Apr 9–Apr 16 (~60 days after transplanting) |
Spacing: 4 per square foot (square-foot-gardening spacing). Mature height: 1-2 ft.
Plant alongside it in zone 9b
These go outside within two weeks of sweet William in zone 9b, so one planting day can cover them.
- NasturtiumFeb 22–Mar 1
- MarigoldFeb 22–Mar 1
- Bells of IrelandFeb 8–Feb 15
- CarnationFeb 8–Feb 15
- Orlaya (Laceflower)Feb 8–Feb 15
- Phlox (Annual)Feb 8–Feb 15
Sweet William is a cottage-garden staple, grown for dense clusters of small, fragrant flowers that often come bicolor, a ring of contrasting color around each petal's edge. NC State Extension puts it at 1 to 2 feet tall and 6 inches to a foot wide, in pink, purple, red, white and variegated forms, hardy across zones 3a to 9b.
How sweet William fits zone 9's season
Zone 9b's frost-free window runs about 293 days, from February 15 to December 5. Sweet William needs about 60 days from transplant to first bloom.
Sweet William planting windows in every zone
Zone 9b is highlighted. Useful for comparing against a neighbouring zone, or for a garden somewhere else.
| Zone | Start indoors | Sow or plant out | Bloom |
|---|---|---|---|
| 3a & 3b | Apr 11–Apr 18 | May 23–May 30 | Jul 22–Jul 29 |
| 4a & 4b | Mar 27–Apr 3 | May 8–May 15 | Jul 7–Jul 14 |
| 5a & 5b | Mar 22–Mar 29 | May 3–May 10 | Jul 2–Jul 9 |
| 6a & 6b | Mar 7–Mar 14 | Apr 18–Apr 25 | Jun 17–Jun 24 |
| 7a & 7b | Feb 20–Feb 27 | Apr 3–Apr 10 | Jun 2–Jun 9 |
| 8a & 8b | Feb 4–Feb 11 | Mar 18–Mar 25 | May 17–May 24 |
| 9a & 9b (your zone) | Dec 28–Jan 4 | Feb 8–Feb 15 | Apr 9–Apr 16 |
Bloom dates are about 60 days after the sow or plant-out date, not after starting seeds indoors.
Good companions
No well-established companions for sweet William.
Where to buy sweet William seeds
Botanical Interests · True Leaf Market · High Mowing Organic Seeds (each supplier's sweet William seeds)
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See it growing
Search YouTube for "growing sweet William" videos → (a live search, not a hand-picked video; results vary and aren't vetted by us)
← Back to the full zone 9b calendar · Plan your beds in the Garden Designer →
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Growing Sweet William in USDA zone 9b: when to start seeds indoors, when to direct-sow, and when to expect a bloom.
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