Sweet Potato in Zone 9a & 9b
Ipomoea batatas
Yes, sweet potato grows in zones 9a and 9b. Start seeds indoors Dec 21–Dec 28 and plant out Mar 8–Mar 15.
When to plant sweet potato 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 21–Dec 28 |
|---|---|
| Direct sow / transplant outside | Mar 8–Mar 15 |
| Estimated harvest | Jun 26–Jul 3 (~110 days after transplanting) |
Spacing: about 4 square feet per plant (square-foot-gardening spacing). Mature height: 0.5-1 ft.
Plant alongside it in zone 9b
These go outside within two weeks of sweet potato in zone 9b, so one planting day can cover them.
- TomatoMar 1–Mar 8
- Sweet CornFeb 22–Mar 1
- CucumberFeb 22–Mar 1
- ZucchiniFeb 22–Mar 1
- Winter SquashFeb 22–Mar 1
- Ground Cherry (Husk Cherry)Mar 8–Mar 15
Sweet potato isn't related to the regular potato at all. It's grown from slips, which are rooted sprouts started from a mature sweet potato, rather than from seed or a cut tuber. It also wants more heat and a longer season than most gardeners expect, which is why an early indoor start matters even though the plant itself is a vigorous, sprawling vine once it's established.
How sweet potato fits zone 9's season
Zone 9b's frost-free window runs about 293 days, from February 15 to December 5. Sweet potato needs about 110 days from transplant to first harvest.
Sweet Potato 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 | Harvest |
|---|---|---|---|
| 6a & 6b | Feb 28–Mar 7 | May 16–May 23 | Sep 3–Sep 10 |
| 7a & 7b | Feb 13–Feb 20 | May 1–May 8 | Aug 19–Aug 26 |
| 8a & 8b | Jan 28–Feb 4 | Apr 15–Apr 22 | Aug 3–Aug 10 |
| 9a & 9b (your zone) | Dec 21–Dec 28 | Mar 8–Mar 15 | Jun 26–Jul 3 |
| 10a & 10bSpring window | Jan–Apr | Mar–Jun | ~110 days after transplanting |
| 11a & 11bFall window | Oct–Jul | Dec–Sep | ~110 days after transplanting |
Harvest dates are about 110 days after the sow or plant-out date, not after starting seeds indoors.
Good companions
- Bush Beans: Beans fix nitrogen that heavy-feeding sweet potato vines use.
Where to buy sweet potato seeds
None of the seed suppliers we list carries sweet potato seeds right now. A local garden center or a specialty seed house is the place to look.
See why we recommend these suppliers →
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See it growing
Search YouTube for "growing sweet potato" 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 Potato in USDA zone 9b: when to start seeds indoors, when to direct-sow, and when to expect a harvest.
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