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When to Plant Komatsuna in Meagher County, MT

Meagher County, Montana Zone 4b May

May to-do list for Meagher County, Montana

A quick May briefing for Meagher County, Montana gardeners — what's urgent, what's next, and what can wait.

Avg. last frost June 10
Avg. first frost September 8
Soil temp (4") 42°F
Watering High
Pest pressure Low
Daylight 14.8 hrs
A few tasks this May that'll pay off in June
  • Transplants going out: komatsuna
  • Direct-sowing: komatsuna
  • Fall sowing: 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.

Meagher County, Montana is in USDA Zone 4b. The average last spring frost is June 10 and the first fall frost is September 8, giving you a growing season of approximately 90 days.

At an elevation of 5,072 feet, Meagher County receives approximately 14.2 inches of rainfall annually with predominantly loam soil. Summer highs average 83°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.

Meagher County, MT (Zone 4b) Very short season
90 days
Last Spring Frost June 10
90 growing days
First Fall Frost September 8

Meagher County Soil Profile

Soil Type

Loam

Soil pH

6.5-8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (28 days to spare)
Start indoors: Apr 16 Transplant: May 28 🍅 Harvest: Jul 2 – Aug 6
Recommended (50%) ✓ Fits season (20 days to spare)
Start indoors: Apr 29 Transplant: Jun 10 🍅 Harvest: Jul 15 – Aug 19
Safe Start (90%) ✓ Fits season (21 days to spare)
Start indoors: May 13 Transplant: Jun 24 🍅 Harvest: Jul 29 – Sep 2

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 Meagher County

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

Soil pH

Your soil pH (6.5–8.0) overlaps with Komatsuna's range (6.0–7.5), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.7%). Annual compost additions will help Komatsuna.

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

2
successive plantings in your 90-day season

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

For a dedicated fall crop, sow by Jun 16.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.7″/week
You supply
0.4″/week
Watering frequency 1-2 times/week
Season total 324 gal / 100 sq ft
Drought risk

Water stress score is 8/10 — consider drought-tolerant varieties and mulching

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" 0" ❄️ Dormant
Feb 0.8" 0" ❄️ Dormant
Mar 1.4" 0" ❄️ Dormant
Apr 1.4" 0" ❄️ Dormant
May 1.9" 0" ❄️ Dormant
Jun 4.3" 0.9" 3.4" 🚿 Regular watering
Jul 4.3" 1.1" 3.2" 🚿 Regular watering
Aug 4.3" 1.5" 2.8" 🚿 Regular watering
Sep 4.3" 1.1" 3.2" 🚿 Regular watering
Oct 1.3" 0" ❄️ Dormant
Nov 1" 0" ❄️ Dormant
Dec 0.9" 0" ❄️ Dormant

Water needs are for active growing months only (Jun–Sep in Meagher 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 ~521 GDD — county provides 1,102 GDD Excellent fit

Komatsuna Planting Timeline — Meagher County, MT

Komatsuna Planting Calendar

Activity When Date Range
Start Indoors April 29 Apr 29 – May 13
Transplant Outdoors June 10 Jun 10 – Jun 24
Direct Sow June 3 Jun 3 – Jun 24
Harvest July 15 Jul 15 – Aug 19
Fall Sowing June 16 Jun 16 – Jun 30

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

1"/week · 1-2 times/week

📅 Days to Maturity

35–50 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 4b

📆 Growing Season

90 days in Meagher County

Growing Tips for Komatsuna in Meagher County

Direct sow Komatsuna outdoors after June 10 in Meagher County when soil has warmed and frost danger has passed.

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

Meagher County receives only 14" of rain annually. Komatsuna needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

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 Meagher County, MT?

Meagher County is in Zone 4b with an average last frost of June 10. Plan your Komatsuna planting based on this frost date — see the calendar above for exact timing.

What planting zone is Meagher County, MT?

Meagher County, Montana is in USDA Hardiness Zone 4b. The average last spring frost is June 10 and first fall frost is September 8.

🌱

Your Meagher County Garden Planner — Free

A 24-page printable planner built for Meagher 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.

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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 Meagher County, MT. 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.