China Aster in Zone 6a & 6b
Callistephus chinensis
Yes, China aster grows in zones 6a and 6b. Start seeds indoors Mar 7–Mar 14 and plant out May 2–May 9.
When to plant China aster in zone 6b
Zones 6a and 6b 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 | Mar 7–Mar 14 |
|---|---|
| Direct sow / transplant outside | May 2–May 9 |
| Estimated bloom | Jul 31–Aug 7 (~90 days after transplanting) |
Spacing: 4 per square foot (square-foot-gardening spacing). Mature height: 1.5-2.5 ft.
Plant alongside it in zone 6b
These go outside within two weeks of China aster in zone 6b, so one planting day can cover them.
- NasturtiumMay 2–May 9
- MarigoldMay 2–May 9
- Ageratum (Flossflower)May 2–May 9
- Annual Geranium (Pelargonium)May 2–May 9
- Butterfly Weed (Asclepias)May 2–May 9
- Campanula (Bellflower)May 2–May 9
China aster is not related to the perennial garden asters despite the common name; it's a true annual grown from seed each year for its full, peony-like cut-flower blooms.
How China aster fits zone 6's season
Zone 6b's frost-free window runs about 173 days, from April 25 to October 15. China aster needs about 90 days from transplant to first bloom.
China Aster planting windows in every zone
Zone 6b 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 27–Jun 3 | Aug 25–Sep 1 |
| 3a & 3b | Apr 11–Apr 18 | Jun 6–Jun 13 | Sep 4–Sep 11 |
| 4a & 4b | Mar 27–Apr 3 | May 22–May 29 | Aug 20–Aug 27 |
| 5a & 5b | Mar 22–Mar 29 | May 17–May 24 | Aug 15–Aug 22 |
| 6a & 6b (your zone) | Mar 7–Mar 14 | May 2–May 9 | Jul 31–Aug 7 |
| 7a & 7b | Feb 20–Feb 27 | Apr 17–Apr 24 | Jul 16–Jul 23 |
| 8a & 8b | Feb 4–Feb 11 | Apr 1–Apr 8 | Jun 30–Jul 7 |
| 9a & 9b | Dec 28–Jan 4 | Feb 22–Mar 1 | May 23–May 30 |
| 10a & 10b | Dec 12–Dec 19 | Feb 6–Feb 13 | May 7–May 14 |
| 11a & 11b | Nov 13–Nov 20 | Jan 8–Jan 15 | Apr 8–Apr 15 |
Bloom dates are about 90 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 China aster.
Where to buy China aster seeds
None of the seed suppliers we list carries China aster seeds right now. A local garden center or a specialty seed house is the place to look.
See why we recommend these suppliers →
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 clear consensus of positive, independent reviews, or ones we bought and use ourselves. Each item on our gear page says which.
See it growing
Search YouTube for "growing China aster" videos → (a live search, not a hand-picked video; results vary and aren't vetted by us)
← Back to the full zone 6b calendar · Plan your beds in the Garden Designer →
Pin this for later
Growing China Aster in USDA zone 6b: when to start seeds indoors, when to direct-sow, and when to expect a bloom.
Save to Pinterest