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When to Plant Komatsuna in Thompson, MB

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.

Thompson, Manitoba is in USDA Zone 3b. The average last spring frost is May 25 and the first fall frost is September 29, giving you a growing season of approximately 127 days.

At an elevation of 728 feet, Thompson receives approximately 11.2 inches of rainfall annually with predominantly black chernozem soil. Summer highs average 66°F, so choose short-season varieties of Komatsuna to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Komatsuna successfully. Mulch heavily to conserve soil moisture.

Thompson, MB (Zone 3b) Short season
127 days
Last Spring Frost May 25
127 growing days
First Fall Frost September 29

Thompson Soil Profile

Soil Type

Black Chernozem

Soil pH

6.0-7.0

Drainage

Well Drained

Komatsuna Planting Timeline — Thompson, MB

Komatsuna Planting Calendar

Activity When Date Range
Start Indoors April 13 Apr 13 – Apr 27
Transplant Outdoors May 25 May 25 – Jun 8
Direct Sow May 18 May 18 – Jun 8
Harvest June 29 Jun 29 – Aug 3
Fall Sowing July 7 Jul 7 – Jul 21

Plant 0.5" deep · 6" apart · Rows 12" apart

Month-by-Month Timeline

MonthActivities
January
February
March
April Start Indoors
May Transplant Outdoors Direct Sow
June Transplant Outdoors Direct Sow Harvest
July Fall Sowing Harvest
August Harvest
September
October
November
December

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

Moderate — regular watering

📅 Days to Maturity

35–50 days

🧪 Soil pH

Needs 6–7.5 · Your soil: N/A

🗺️ USDA Zone

Zone 3b

📆 Growing Season

127 days in Thompson

Growing Tips for Thompson

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

  • Strawberries

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Komatsuna in Thompson, MB?

Thompson is in Zone 3b with an average last frost of May 25. Plan your Komatsuna planting based on this frost date — see the calendar above for exact timing.

What planting zone is Thompson, MB?

Thompson, Manitoba is in USDA Hardiness Zone 3b. The average last spring frost is May 25 and first fall frost is September 29.

🌱

Your Thompson Garden Planner — Free

A 22-page printable planner built for Thompson (Zone 3b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

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Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Thompson, MB. Local conditions may vary. Last updated: June 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.