When to plant Aster
China asters are bushy annuals giving a flush of richly coloured, daisy-like blooms in late summer and fall. They're prone to a soil-borne wilt, so it pays to plant them in a fresh spot each year. Excellent, long-lasting cut flowers.
Companions: A late-season pollinator favourite for the cutting bed
How to grow Aster
Aster is usually started indoors and transplanted out, giving this half-hardy crop the head start it needs. Give it full sun and space plants about 10 inches apart. It takes roughly 90 days from planting to its first harvest, so count that against your frost dates to be sure it can finish. Classic companions include a late-season pollinator favourite for the cutting bed.
Grower's tip: China asters are tender annuals for late-summer colour; rotate their spot each year to dodge wilt.
When to plant Aster by USDA zone
Timing shifts with your climate — the same aster goes in weeks earlier in a mild zone than a cold one. Find your zone below for its planting window, or open that zone's full calendar.
| Zone | When to plant |
|---|---|
| Zone 1a | Start seeds indoors May 4–May 18 Transplant outdoors Jun 15–Jun 29 |
| Zone 1b | Start seeds indoors Apr 29–May 13 Transplant outdoors Jun 10–Jun 24 |
| Zone 2a | Start seeds indoors Apr 24–May 8 Transplant outdoors Jun 5–Jun 19 |
| Zone 2b | Start seeds indoors Apr 18–May 2 Transplant outdoors May 30–Jun 13 |
| Zone 3a | Start seeds indoors Apr 13–Apr 27 Transplant outdoors May 25–Jun 8 |
| Zone 3b | Start seeds indoors Apr 8–Apr 22 Transplant outdoors May 20–Jun 3 |
| Zone 4a | Start seeds indoors Apr 3–Apr 17 Transplant outdoors May 15–May 29 |
| Zone 4b | Start seeds indoors Mar 29–Apr 12 Transplant outdoors May 10–May 24 |
| Zone 5a | Start seeds indoors Mar 24–Apr 7 Transplant outdoors May 5–May 19 |
| Zone 5b | Start seeds indoors Mar 19–Apr 2 Transplant outdoors Apr 30–May 14 |
| Zone 6a | Start seeds indoors Mar 10–Mar 24 Transplant outdoors Apr 21–May 5 |
| Zone 6b | Start seeds indoors Mar 4–Mar 18 Transplant outdoors Apr 15–Apr 29 |
| Zone 7a | Start seeds indoors Feb 24–Mar 10 Transplant outdoors Apr 7–Apr 21 |
| Zone 7b | Start seeds indoors Feb 18–Mar 4 Transplant outdoors Apr 1–Apr 15 |
| Zone 8a | Start seeds indoors Feb 8–Feb 22 Transplant outdoors Mar 22–Apr 5 |
| Zone 8b | Start seeds indoors Feb 1–Feb 15 Transplant outdoors Mar 15–Mar 29 |
| Zone 9a | Start seeds indoors Jan 17–Jan 31 Transplant outdoors Feb 28–Mar 14 |
| Zone 9b | Start seeds indoors Jan 4–Jan 18 Transplant outdoors Feb 15–Mar 1 |
| Zone 10a | Start seeds indoors Dec 20–Jan 3 Transplant outdoors Jan 31–Feb 14 |
| Zone 10b | Start seeds indoors Dec 4–Dec 18 Transplant outdoors Jan 15–Jan 29 |
| Zone 11a | Start seeds indoors Nov 20–Dec 4 Transplant outdoors Jan 1–Jan 15 |
| Zone 11b | Start seeds indoors Nov 20–Dec 4 Transplant outdoors Jan 1–Jan 15 |
| Zone 12a | Start seeds indoors Nov 20–Dec 4 Transplant outdoors Jan 1–Jan 15 |
| Zone 12b | Start seeds indoors Nov 20–Dec 4 Transplant outdoors Jan 1–Jan 15 |
| Zone 13a | Start seeds indoors Nov 20–Dec 4 Transplant outdoors Jan 1–Jan 15 |
| Zone 13b | Start seeds indoors Nov 20–Dec 4 Transplant outdoors Jan 1–Jan 15 |