Spinach in Zone 10a & 10b
Spinacia oleracea
Yes, spinach grows in zones 10a and 10b. Start seeds indoors in Aug–Dec and plant out in Sep–Jan. For a fall crop, start seeds indoors in Aug–Dec and plant out in Sep–Jan.
When to plant spinach in zone 10b
Zones 10a and 10b share the same average frost dates, so this page covers both.
Method: Start indoors: Start indoors from seed, then transplant outside. In your zone it needs a head start on the heat that direct-sowing elsewhere doesn't require.
| Window | Fall window |
|---|---|
| Start indoors | Aug–Dec |
| Direct sow / transplant outside | Sep–Jan |
| Estimated harvest | ~40 days after transplanting |
Spacing: 9 per square foot (square-foot-gardening spacing). Mature height: 0.5-1 ft.
Zone 10b dates sourced from growinginthegarden.com.
Fall window: the last sowing date is the average first frost minus days to maturity, the method in Purdue Extension's fall garden guide, which lists spinach for late-summer planting.
Plant alongside it in zone 10b
These go outside within two weeks of spinach in zone 10b, so one planting day can cover them.
Spinach is one of the fastest, most cold-tolerant greens you can grow, direct-seeded a full month before your last frost, but it's also quick to bolt once the weather warms, so the growing window is short and worth planning around rather than fighting.
How spinach fits zone 10's season
Zone 10b's frost-free window runs about 324 days, from January 30 to December 20. Spinach needs about 40 days from sowing to first harvest.
Spinach planting windows in every zone
Zone 10b is highlighted. Useful for comparing against a neighbouring zone, or for a garden somewhere else.
| Zone | Start indoors | Sow or plant out | Harvest |
|---|---|---|---|
| 2a & 2bSpring window | Not usually | Apr 22–Apr 29 | Jun 1–Jun 8 |
| Fall window | Not usually | Jul 9–Jul 23 | Aug 18–Sep 1 |
| 3a & 3bSpring window | Not usually | May 2–May 9 | Jun 11–Jun 18 |
| Fall window | Not usually | Jul 13–Jul 27 | Aug 22–Sep 5 |
| 4a & 4bSpring window | Not usually | Apr 17–Apr 24 | May 27–Jun 3 |
| Fall window | Not usually | Jul 28–Aug 11 | Sep 6–Sep 20 |
| 5a & 5bSpring window | Not usually | Apr 12–Apr 19 | May 22–May 29 |
| Fall window | Not usually | Aug 12–Aug 26 | Sep 21–Oct 5 |
| 6a & 6bSpring window | Not usually | Mar 28–Apr 4 | May 7–May 14 |
| Fall window | Not usually | Aug 22–Sep 5 | Oct 1–Oct 15 |
| 7a & 7bSpring window | Not usually | Mar 13–Mar 20 | Apr 22–Apr 29 |
| Fall window | Not usually | Sep 1–Sep 15 | Oct 11–Oct 25 |
| 8a & 8bSpring window | Not usually | Feb 25–Mar 4 | Apr 6–Apr 13 |
| Fall window | Not usually | Sep 17–Oct 1 | Oct 27–Nov 10 |
| 9a & 9bSpring window | Not usually | Jan 18–Jan 25 | Feb 27–Mar 6 |
| Fall window | Not usually | Oct 12–Oct 26 | Nov 21–Dec 5 |
| 10a & 10bFall window (your zone) | Aug–Dec | Sep–Jan | ~40 days after transplanting |
Harvest dates are about 40 days after the sow or plant-out date.
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
- Radish: Radish breaks up soil and matures quickly alongside spinach.
Where to buy spinach seeds
Botanical Interests · Burpee · High Mowing Organic Seeds (each supplier's spinach seeds)
Varieties we recommend, and where to get them:
- Space (F1): Rated by the seed company with high resistance across a wide range of downy mildew races (1-3, 5, 6, 8, 9, 11, 12, 14, 16, 19), a smooth-leaf, all-season type worth considering where downy mildew has been a recurring problem. Buy: Botanical Interests · Burpee · High Mowing Organic Seeds Full notes
- Bloomsdale Long Standing: An open-pollinated heirloom, savoyed rather than smooth-leaf, that Cornell's disease-resistance factsheet lists as resistant to Downy Mildew races 1-12, 14 and 15. Buy: True Leaf Market · Burpee Full notes
See why we recommend these suppliers →
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See it growing
Search YouTube for "growing spinach" videos → (a live search, not a hand-picked video; results vary and aren't vetted by us)
← Back to the full zone 10b calendar · Plan your beds in the Garden Designer →
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Growing Spinach in USDA zone 10b: when to start seeds indoors, when to direct-sow, and when to expect a harvest.
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