When to Plant Komatsuna in USDA Zone 3b
Your June gardening checklist
Here's what deserves your attention in Zone 3b this month. Everything below is tailored to Zone 3b and timed around your local frost dates.
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Sow komatsuna in trays indoors
Give them 6–8 weeks indoors before the last frost and you'll transplant into warm soil with seedlings that are already leaping.
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Basket week: komatsuna
If you can't use it all right away, check the food-preservation section of your planner.
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Get komatsuna in for a late-season harvest
A row cover ready in the garage extends your harvest by weeks once the nights turn cold.
Get ahead of July
- First harvests: komatsuna
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 3b, the average last spring frost is around May 10 and the first fall frost is around September 22, giving you a growing season of approximately 135 days.
Komatsuna Planting Timeline — Zone 3b
Where Is USDA Zone 3b?
The map below highlights the states that contain Zone 3b. Click any state to see the Komatsuna planting schedule for that location.
Komatsuna Planting Calendar — Zone 3b
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 29 | Mar 29 – Apr 12 |
| Transplant Outdoors | May 10 | May 10 – May 24 |
| Direct Sow | May 3 | May 3 – May 24 |
| Harvest | June 14 | Jun 14 – Jul 19 |
| Fall Sowing | June 30 | Jun 30 – Jul 14 |
Plant 0.5" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Start Indoors |
| May | Transplant Outdoors Direct Sow |
| June | Fall Sowing Harvest |
| July | Fall Sowing Harvest |
| August | — |
| September | — |
| October | — |
| November | — |
| December | — |
Free Zone 3b Planting Calendar PDF
Know exactly when to plant every crop in your zone. Get a printable month-by-month calendar customized for Zone 3b 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 -30°F average annual minimum
Growing Season
135 days (Zone 3b average)
Planting Specifications
| Planting Depth | 0.5 inches |
| Plant Spacing | 6 inches apart |
| Row Spacing | 12 inches between rows |
Succession Planting Komatsuna in Zone 3b
Sow every 4 weeks for continuous harvest throughout the season.
Growing Tips for Komatsuna in Zone 3b
Zone 3b has a short growing season (~135 days). Start Komatsuna indoors early and use season-extension techniques like row covers and cold frames.
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
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- Proven pairings for 200+ vegetables, herbs, flowers, and fruits
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Saving Komatsuna Seeds
Recommended for Your Garden
Full-spectrum LED lights for starting seeds indoors when daylight is limited.
Warm soil for faster germination of heat-loving crops like tomatoes and peppers.
Protect plants from frost, wind, and pests while letting light and water through.
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 3b?
In Zone 3b, plan your Komatsuna planting around the average last frost date of May 10. Start seeds indoors around March 29. Direct sow outdoors around May 3. Transplant seedlings around May 10.
Can Komatsuna grow in Zone 3b?
Yes, Komatsuna can grow well in Zone 3b, hardy in USDA zones 2a through 11b. Zone 3b has a growing season of approximately 135 days, which is sufficient for Komatsuna (35-50 days to maturity).
When can I harvest Komatsuna in Zone 3b?
In Zone 3b, expect to harvest Komatsuna from June 14 – July 19. Komatsuna takes 35-50 days from planting to harvest.
What is the last frost date for Zone 3b?
The average last spring frost in Zone 3b is around May 10, and the first fall frost is around September 22. This gives a growing season of approximately 135 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 3b Garden Planner — Free
A 22-page printable planner tailored to Zone 3b. Planting dates, monthly task lists, harvest log, seed inventory, and succession charts — everything you need to plan a full season.