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When to Plant Komatsuna in Dickinson County, MI

Dickinson County, Michigan Zone 4b May

Dickinson County, Michigan gardeners: here's your May plan

We've pulled the most time-sensitive tasks for Dickinson County, Michigan this May and put them front and centre. Tackle them in order.

Avg. last frost May 12
Avg. first frost October 9
Soil temp (4") 54°F
Watering Low
Pest pressure Low
Daylight 14.8 hrs
  1. Move komatsuna into the garden

    Your last frost (May 12) has passed. These warm-season crops can handle outdoor soil now.

  2. Sow komatsuna where they'll grow

    Sow every 2 weeks for a continuous harvest. A single big planting means a single big glut.

June will be here before you know it — start on
  • Starting indoors: komatsuna
  • First harvests: komatsuna

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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.

Dickinson County, Michigan is in USDA Zone 4b. The average last spring frost is May 12 and the first fall frost is October 9, giving you a growing season of approximately 150 days.

At an elevation of 892 feet, Dickinson County receives approximately 32.2 inches of rainfall annually with predominantly silt loam soil. Summer highs average 82°F, so choose short-season varieties of Komatsuna to ensure they mature before fall.

Dickinson County, MI (Zone 4b) Moderate season
150 days
Last Spring Frost May 12
150 growing days
First Fall Frost October 9

Dickinson County Soil Profile

Soil Type

Silt Loam

Soil pH

6-7.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (79 days to spare)
Start indoors: Mar 23 Transplant: May 4 🍅 Harvest: Jun 8 – Jul 13
Recommended (50%) ✓ Fits season (80 days to spare)
Start indoors: Mar 31 Transplant: May 12 🍅 Harvest: Jun 16 – Jul 21
Safe Start (90%) ✓ Fits season (92 days to spare)
Start indoors: Apr 16 Transplant: May 28 🍅 Harvest: Jul 2 – Aug 6

Percentages indicate frost risk at transplant. The 70% safe window means there is a 30% chance of frost after transplant — suitable for cold-hardy crops or gardeners with frost protection. The 90% safe window is best for tender plants.

Soil Compatibility in Dickinson County

How your county's soil matches Komatsuna's growing requirements.

Soil pH

Your soil pH (6.0–7.3) is within Komatsuna's preferred range (6.0–7.5).

Soil Texture

The silt loam soil in Dickinson County is excellent for Komatsuna — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is excellent (4.1%) — Komatsuna will thrive.

How to Plant Komatsuna

0.5"
Planting Depth
6"
Between Plants
12"
Between Rows

Fall planting: Sow 12 weeks before your first frost date for a fall harvest.

Succession Planting Komatsuna

5
successive plantings in your 150-day season

Sow every 4 weeks. Last sowing by Aug 20 to harvest before frost.

For a dedicated fall crop, sow by Jul 17.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.9″/week
You supply
0.1″/week
Watering frequency Only during dry spells
Season total 131 gal / 100 sq ft

Monthly Watering Guide for Komatsuna

Komatsuna needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Komatsuna Needs Rainfall You Supplement Action
Jan 1.3" 0" ❄️ Dormant
Feb 1.4" 0" ❄️ Dormant
Mar 2.3" 0" ❄️ Dormant
Apr 3.3" 0" ❄️ Dormant
May 4.3" 3.8" 0.5" 💧 Light watering
Jun 4.3" 3.7" 0.6" 💧 Light watering
Jul 4.3" 3.8" 0.5" 💧 Light watering
Aug 4.3" 3.1" 1.2" 💧 Light watering
Sep 4.3" 2.9" 1.4" 💧 Light watering
Oct 4.3" 2.3" 2" 💧 Light watering
Nov 2.1" 0" ❄️ Dormant
Dec 2.1" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Dickinson County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Komatsuna Heat Requirements (GDD)

What are Growing Degree Days (GDD)?

Growing Degree Days measure the total warmth your plants receive during the growing season. Think of it as a "heat bank" — every day above 50°F deposits warmth that helps your plants grow.

Each plant needs a certain amount of accumulated heat to mature. If your county provides more GDD than the plant needs, it's a great fit. If it's close, you may want to choose faster-maturing varieties or start seeds indoors to get a head start.

Komatsuna needs ~489 GDD — county provides 1,725 GDD Excellent fit

Komatsuna Planting Timeline — Dickinson County, MI

Komatsuna Planting Calendar

Activity When Date Range
Start Indoors March 31 Mar 31 – Apr 14
Transplant Outdoors May 12 May 12 – May 26
Direct Sow May 5 May 5 – May 26
Harvest June 16 Jun 16 – Jul 21
Fall Sowing July 17 Jul 17 – Jul 31

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

1"/week · Only during dry spells

📅 Days to Maturity

35–50 days

🧪 Soil pH

Needs 6–7.5 · Your soil: ideal

🗺️ USDA Zone

Zone 4b

📆 Growing Season

150 days in Dickinson County

Growing Tips for Komatsuna in Dickinson County

Direct sow Komatsuna outdoors after May 12 in Dickinson County when soil has warmed and frost danger has passed.

Your generous 150.0-day season in Dickinson County allows multiple plantings of Komatsuna. Sow every 17.0 days for continuous harvest.

Common pests for Komatsuna in this region include cabbage worm and flea beetles. Use row covers early in the season and inspect plants weekly.

General growing tips

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 Dickinson County, MI?

Dickinson County is in Zone 4b with an average last frost of May 12. Plan your Komatsuna planting based on this frost date — see the calendar above for exact timing.

What planting zone is Dickinson County, MI?

Dickinson County, Michigan is in USDA Hardiness Zone 4b. The average last spring frost is May 12 and first fall frost is October 9.

🌱

Your Dickinson County Garden Planner — Free

A 24-page printable planner built for Dickinson County (Zone 4b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

Instant PDF download. No spam, unsubscribe any time.

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

Sources & credits

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