Komatsuna in Zone 10a & 10b
Brassica rapa var. perviridis
Yes, komatsuna grows in zones 10a and 10b. Plant it outside Jan 16–Jan 23.
When to plant komatsuna in zone 10b
Zones 10a and 10b share the same average frost dates, so this page covers both.
Method: Direct sow: Direct-sow outside. It doesn't transplant well, or doesn't need the extra time indoors.
| Start indoors | Not typically started indoors |
|---|---|
| Direct sow / transplant outside | Jan 16–Jan 23 |
| Estimated harvest | Feb 25–Mar 4 (~40 days after direct-sowing) |
Spacing: 4 per square foot (square-foot-gardening spacing). Mature height: 1-1.5 ft.
Plant alongside it in zone 10b
These go outside within two weeks of komatsuna in zone 10b, so one planting day can cover them.
- Flower SproutsJan 16–Jan 23
- Gai Lan (Chinese Broccoli)Jan 16–Jan 23
- KalettesJan 16–Jan 23
- Broccoli Rabe (Raab)Jan 9–Jan 16
- MizunaJan 9–Jan 16
- TatsoiJan 9–Jan 16
Komatsuna is a fast, mild-flavored Asian brassica green, notably more heat- and cold-tolerant than spinach while offering a similar leaf texture and taste, which makes it a useful stand-in during the stretches of the season spinach won't tolerate.
How komatsuna fits zone 10's season
Zone 10b's frost-free window runs about 324 days, from January 30 to December 20. Komatsuna needs about 40 days from sowing to first harvest.
Komatsuna 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 & 2b | Not usually | May 6–May 13 | Jun 15–Jun 22 |
| 3a & 3b | Not usually | May 16–May 23 | Jun 25–Jul 2 |
| 4a & 4b | Not usually | May 1–May 8 | Jun 10–Jun 17 |
| 5a & 5b | Not usually | Apr 26–May 3 | Jun 5–Jun 12 |
| 6a & 6b | Not usually | Apr 11–Apr 18 | May 21–May 28 |
| 7a & 7b | Not usually | Mar 27–Apr 3 | May 6–May 13 |
| 8a & 8b | Not usually | Mar 11–Mar 18 | Apr 20–Apr 27 |
| 9a & 9b | Not usually | Feb 1–Feb 8 | Mar 13–Mar 20 |
| 10a & 10b (your zone) | Not usually | Jan 16–Jan 23 | Feb 25–Mar 4 |
| 11a & 11b | Not usually | Dec 18–Dec 25 | Jan 27–Feb 3 |
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 (including the daikon form) is a documented trap crop for flea beetles, which prefer its mustard oils over other brassicas and can be sacrificed or pulled once infested: the same research cited on the radish page.
Where to buy komatsuna seeds
True Leaf Market (each supplier's komatsuna seeds)
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 komatsuna" 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 →
Pin this for later
Growing Komatsuna in USDA zone 10b: when to start seeds indoors, when to direct-sow, and when to expect a harvest.
Save to Pinterest