When to Plant Komatsuna in USDA Zone 10b
June in Zone 10b — your action list
We've pulled the most time-sensitive tasks for Zone 10b this June and put them front and centre. Tackle them in order.
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Survive, don't thrive
June-August is endurance gardening. Keep okra, peppers, sweet potatoes, and southern peas alive. Harvest everything daily before the heat damages produce on the vine.
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Start fall tomato seeds indoors
Yes, indoors — under lights or in AC. They'll be ready to transplant in August when temperatures briefly moderate.
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Add compost to empty beds
Empty beds get a thick layer of compost + mulch to suppress weeds and feed the soil for fall planting.
Komatsuna (Japanese mustard spinach) is a versatile Asian green with glossy, dark leaves and a mild, sweet flavor. It is extremely cold-hardy and heat-tolerant.
In Zone 10b, the average last spring frost is around January 1 and the first fall frost is around December 31, giving you a growing season of approximately 364 days.
Komatsuna Planting Timeline — Zone 10b
Where Is USDA Zone 10b?
The map below highlights the states that contain Zone 10b. Click any state to see the Komatsuna planting schedule for that location.
Komatsuna Planting Calendar — Zone 10b
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | December 4 | Dec 4 – Dec 18 |
| Transplant Outdoors | January 1 | Jan 1 – Jan 15 |
| Direct Sow | December 11 | Dec 11 – Jan 1 |
| Harvest | February 5 | Feb 5 – Mar 12 |
| Fall Sowing | November 5 | Nov 5 – Nov 19 |
Plant 0.5" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | Transplant Outdoors Direct Sow |
| February | Harvest |
| March | Harvest |
| April | — |
| May | — |
| June | — |
| July | — |
| August | — |
| September | — |
| October | — |
| November | Fall Sowing |
| December | Start Indoors Direct Sow |
Free Zone 10b Planting Calendar PDF
Know exactly when to plant every crop in your zone. Get a printable month-by-month calendar customized for Zone 10b with start dates, transplant windows, and harvest times.
Growing Conditions
Sun
Partial Shade (3-6 hours)
💧 Water
Moderate — regular watering
Days to Maturity
35–50 days
Soil pH
6 – 7.5
Zone Temperature Range
35°F to 40°F average annual minimum
Growing Season
365 days (Zone 10b average)
Planting Specifications
| Planting Depth | 0.5 inches |
| Plant Spacing | 6 inches apart |
| Row Spacing | 12 inches between rows |
Succession Planting Komatsuna in Zone 10b
Sow every 4 weeks for continuous harvest throughout the season.
Growing Tips for Komatsuna in Zone 10b
Zone 10b offers a long growing season (~365 days). You can plant Komatsuna earlier and may get multiple harvests.
Direct sow in spring or fall. One of the most forgiving Asian greens for all seasons. Harvest outer leaves or cut whole plants. Excellent for stir-fries, soups, or salads.
Companion Planting
Good Companions
Avoid Planting Near
The Gardener's Encyclopedia to Companion Planting
The pairings that make vegetables, herbs, and flowers grow better — and the ones that quietly wreck a bed.
- Proven pairings for 200+ vegetables, herbs, flowers, and fruits
- Full seed-starting + planting schedule with timing and spacing
- Bonus: square-foot gardening guide + printable seasonal planners
Saving Komatsuna Seeds
Recommended for Your Garden
Reduce heat stress and sun scorch in hot climates with UV-stabilized shade cloth.
Start seeds indoors with reusable cell trays and humidity domes.
Test your soil pH, nitrogen, phosphorus, and potassium levels before planting.
Related Plants
Komatsuna in Other Zones
Komatsuna by State
- Alabama
- Alaska
- Arizona
- Arkansas
- California
- Colorado
- Connecticut
- Delaware
- Florida
- Georgia
- Hawaii
- Idaho
- Illinois
- Indiana
- Iowa
- Kansas
- Kentucky
- Louisiana
- Maine
- Maryland
- Massachusetts
- Michigan
- Minnesota
- Mississippi
- Missouri
- Montana
- Nebraska
- Nevada
- New Hampshire
- New Jersey
- New Mexico
- New York
- North Carolina
- North Dakota
- Ohio
- Oklahoma
- Oregon
- Pennsylvania
- Rhode Island
- South Carolina
- South Dakota
- Tennessee
- Texas
- Utah
- Vermont
- Virginia
- Washington
- West Virginia
- Wisconsin
- Wyoming
Frequently Asked Questions
When should I plant Komatsuna in Zone 10b?
In Zone 10b, plan your Komatsuna planting around the average last frost date of January 1. Start seeds indoors around December 4. Direct sow outdoors around December 11. Transplant seedlings around January 1.
Can Komatsuna grow in Zone 10b?
Yes, Komatsuna can grow well in Zone 10b, hardy in USDA zones 2a through 11b. Zone 10b has a growing season of approximately 364 days, which is sufficient for Komatsuna (35-50 days to maturity).
When can I harvest Komatsuna in Zone 10b?
In Zone 10b, expect to harvest Komatsuna from February 5 – March 12. Komatsuna takes 35-50 days from planting to harvest.
What is the last frost date for Zone 10b?
The average last spring frost in Zone 10b is around January 1, and the first fall frost is around December 31. This gives a growing season of approximately 364 days. These are 50% probability dates — actual frost dates vary year to year.
What should I plant next to Komatsuna?
Good companion plants for Komatsuna include Lettuce, Spinach, Radish. These companions can help with pest control, pollination, and nutrient sharing.
Your Zone 10b Garden Planner — Free
A 22-page printable planner tailored to Zone 10b. Planting dates, monthly task lists, harvest log, seed inventory, and succession charts — everything you need to plan a full season.