Osteospermum in Zone 4a & 4b
Osteospermum ecklonis
Yes, osteospermum grows in zones 4a and 4b. Start seeds indoors Mar 20–Mar 27 and plant out May 22–May 29.
When to plant osteospermum in zone 4b
Zones 4a and 4b 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 20–Mar 27 |
|---|---|
| Direct sow / transplant outside | May 22–May 29 |
| Estimated bloom | Aug 20–Aug 27 (~90 days after transplanting) |
Spacing: 1 per square foot (square-foot-gardening spacing). Mature height: 1-3 ft.
Plant alongside it in zone 4b
These go outside within two weeks of osteospermum in zone 4b, so one planting day can cover them.
- NasturtiumMay 22–May 29
- MarigoldMay 22–May 29
- Ageratum (Flossflower)May 22–May 29
- Annual Geranium (Pelargonium)May 22–May 29
- Butterfly Weed (Asclepias)May 22–May 29
- Campanula (Bellflower)May 22–May 29
Two different plants are sold as African daisy, and knowing which you have decides how you treat it.
How osteospermum fits zone 4's season
Zone 4b's frost-free window runs about 128 days, from May 15 to September 20. Osteospermum needs about 90 days from transplant to first bloom.
Osteospermum planting windows in every zone
Zone 4b is highlighted. Useful for comparing against a neighbouring zone, or for a garden somewhere else.
| Zone | Start indoors | Sow or plant out | Bloom |
|---|---|---|---|
| 4a & 4b (your zone) | Mar 20–Mar 27 | May 22–May 29 | Aug 20–Aug 27 |
| 5a & 5b | Mar 15–Mar 22 | May 17–May 24 | Aug 15–Aug 22 |
| 6a & 6b | Feb 28–Mar 7 | May 2–May 9 | Jul 31–Aug 7 |
| 7a & 7b | Feb 13–Feb 20 | Apr 17–Apr 24 | Jul 16–Jul 23 |
| 8a & 8b | Jan 28–Feb 4 | Apr 1–Apr 8 | Jun 30–Jul 7 |
| 9a & 9b | Dec 21–Dec 28 | Feb 22–Mar 1 | May 23–May 30 |
| 10a & 10b | Dec 5–Dec 12 | Feb 6–Feb 13 | May 7–May 14 |
Bloom dates are about 90 days after the sow or plant-out date, not after starting seeds indoors.
Good companions
No well-established companions for osteospermum.
Where to buy osteospermum seeds
True Leaf Market (each supplier's osteospermum seeds)
See why we recommend these suppliers →
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See it growing
Search YouTube for "growing osteospermum" videos → (a live search, not a hand-picked video; results vary and aren't vetted by us)
← Back to the full zone 4b calendar · Plan your beds in the Garden Designer →
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Growing Osteospermum in USDA zone 4b: when to start seeds indoors, when to direct-sow, and when to expect a bloom.
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