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When to plant Mitsuba in Fallon County, MT

Mitsuba planted in Fallon County between May 13 and June 3 matures in 50–70 days — well before the September 20 first frost. A second sowing from June 28 to July 12 extends the harvest into fall.

When to Plant Mitsuba in Fallon County, MT

Fallon County, Montana Zone 4b August

Fallon County, Montana gardeners: here's your August plan

If you only do a handful of things in the garden this August, make it these. They're sequenced around your zone's frost timing.

Avg. last frost May 20
Avg. first frost September 20
Soil temp (4") 53°F
Watering High
Pest pressure High
Daylight 14 hrs
  1. Pick mitsuba

    Don't tug. Use scissors or pruners for clean cuts — torn stems invite disease.

Looking ahead to September
  • First harvests: mitsuba

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Mitsuba (Japanese parsley) is a shade-loving herb with trefoil leaves and a mild celery-parsley flavor. It is essential in Japanese cuisine for soups, salads, and garnishes.

Fallon County, Montana is in USDA Zone 4b. The average last spring frost is May 20 and the first fall frost is September 20, giving you a growing season of approximately 123 days.

At an elevation of 6,441 feet, Fallon County receives approximately 19.8 inches of rainfall annually with predominantly loam soil. Summer highs average 81°F, so choose short-season varieties of Mitsuba to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Mitsuba successfully. Mulch heavily to conserve soil moisture.

Fallon County, MT (Zone 4b) Short season
123 days
Last Spring Frost May 20
123 growing days
First Fall Frost September 20

Fallon County Soil Profile

Soil Type

Loam

Soil pH

6.2-8.3

Drainage

Well Drained

Mitsuba Planting Risk Windows

Early Start (70% safe) ✓ Fits season (17 days to spare)
Start indoors: Apr 2 Transplant: May 7 🍅 Harvest: Jul 2 – Aug 27
Recommended (50%) ✓ Fits season (18 days to spare)
Start indoors: Apr 8 Transplant: May 13 🍅 Harvest: Jul 8 – Sep 2
Safe Start (90%) ✓ Fits season (13 days to spare)
Start indoors: Apr 27 Transplant: Jun 1 🍅 Harvest: Jul 27 – Sep 21

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 Fallon County

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

Soil pH

Your soil pH (6.2–8.3) is more alkaline than Mitsuba prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.2%). Annual compost additions will help Mitsuba.

How to Plant Mitsuba

0.5"
Planting Depth
8"
Between Plants
12"
Between Rows

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

Succession Planting Mitsuba

2
successive plantings in your 123-day season

Sow every 5.7 weeks. Last sowing by Jul 12 to harvest before frost.

For a dedicated fall crop, sow by Jun 28.

Mitsuba 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 425 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Mitsuba

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

Month Mitsuba Needs Rainfall You Supplement Action
Jan 1.3" 0" ❄️ Dormant
Feb 1.3" 0" ❄️ Dormant
Mar 1.8" 0" ❄️ Dormant
Apr 2.1" 0" ❄️ Dormant
May 4.3" 2.7" 1.6" 💧 Light watering
Jun 4.3" 1.4" 2.9" 🚿 Regular watering
Jul 4.3" 1.6" 2.7" 🚿 Regular watering
Aug 4.3" 1.9" 2.4" 🚿 Regular watering
Sep 4.3" 1.6" 2.7" 🚿 Regular watering
Oct 1.7" 0" ❄️ Dormant
Nov 1.2" 0" ❄️ Dormant
Dec 1.2" 0" ❄️ Dormant

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

Mitsuba 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.

Mitsuba needs ~645 GDD — county provides 1,322 GDD Excellent fit

Mitsuba Planting Timeline — Fallon County, MT

Mitsuba Planting Calendar

Activity When Date Range
Start Indoors April 8 Apr 8 – Apr 22
Transplant Outdoors May 13 May 13 – May 27
Direct Sow May 13 May 13 – Jun 3
Harvest July 8 Jul 8 – Sep 2
Fall Sowing June 28 Jun 28 – Jul 12

Plant 0.5" deep · 8" apart · Rows 12" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

1"/week · 1-2 times/week

📅 Days to Maturity

50–70 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 4b

📆 Growing Season

123 days in Fallon County

Growing Tips for Mitsuba in Fallon County

Direct sow Mitsuba outdoors after May 20 in Fallon County when soil has warmed and frost danger has passed.

Common pests for Mitsuba in this region include carrot rust fly and parsleyworm. Use row covers early in the season and inspect plants weekly.

Fallon County receives only 20" of rain annually. Mitsuba needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

General growing tips

Direct sow or start indoors in partial shade. Mitsuba prefers cool, moist conditions. Harvest outer stems as needed. Self-sows readily in shaded garden areas.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Mitsuba in Fallon County, MT?

Fallon County is in Zone 4b with an average last frost of May 20. Plan your Mitsuba planting based on this frost date — see the calendar above for exact timing.

What planting zone is Fallon County, MT?

Fallon County, Montana is in USDA Hardiness Zone 4b. The average last spring frost is May 20 and first fall frost is September 20.

When should I plant Mitsuba in Fallon County, MT?

In Fallon County, MT, plant Mitsuba after the last frost (around May 20) and before the first frost (around September 20). Best results when soil holds above 50°F.

What growing zone is Fallon County, MT for Mitsuba?

Fallon County sits in USDA Zone 4b. Mitsuba grows reliably in zones 4a through 9b, so it's a good fit here.

Can Mitsuba grow in Fallon County's climate?

Yes — Mitsuba grows well in Fallon County's temperate climate. Fallon County averages a 123-day frost-free season, with last frost around May 20 and first frost around September 20.

🌱

Your Fallon County Garden Planner — Free

A 22-page printable planner built for Fallon 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 Fallon County, MT. Local conditions may vary. Last updated: August 2026.

Sources & credits

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