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When to Plant Mitsuba in Glacier County, MT

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.

Glacier County, Montana is in USDA Zone 4a. The average last spring frost is May 22 and the first fall frost is September 18, giving you a growing season of approximately 119 days.

At an elevation of 8,147 feet, Glacier County receives approximately 13.3 inches of rainfall annually with predominantly loam soil. Summer highs average 80ยฐF, 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.

Glacier County, MT (Zone 4a) Short season
119 days
Last Spring Frost May 22
119 growing days
First Fall Frost September 18

Glacier County Soil Profile

Soil Type

Loam

Soil pH

6.3-8.1

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (14 days to spare)
Start indoors: Apr 3 Transplant: May 8 🍅 Harvest: Jul 3 – Aug 28
Recommended (50%) ✓ Fits season (14 days to spare)
Start indoors: Apr 10 Transplant: May 15 🍅 Harvest: Jul 10 – Sep 4
Safe Start (90%) ✓ Fits season (1 days to spare)
Start indoors: Apr 30 Transplant: Jun 4 🍅 Harvest: Jul 30 – Sep 24

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.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.5″/week
You supply
0.6″/week
Watering frequency 1-2 times/week
Season total 674 gal / 100 sq ft
Drought risk

Water stress score is 8/10 โ€” consider drought-tolerant varieties and mulching

Mitsuba needs ~600 GDD — county provides 1,190 GDD Excellent fit

Mitsuba Planting Timeline โ€” Glacier County, MT

Mitsuba Planting Calendar

Activity When Date Range
Start Indoors April 10 Apr 10 โ€“ Apr 24
Transplant Outdoors May 15 May 15 โ€“ May 29
Direct Sow May 15 May 15 โ€“ Jun 5
Fall Sowing June 26 Jun 26 โ€“ Jul 10
Harvest July 10 Jul 10 โ€“ Sep 4

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

Month-by-Month Timeline

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

Growing Conditions

Sun

Partial Shade (3-6 hours)

Water

Moderate โ€” regular watering

Days to Maturity

50โ€“70 days

Soil pH

6 โ€“ 7

USDA Zone

Zone 4a

Growing Season

119 days

Growing Tips for Glacier County

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

Level Up Your Garden

Frequently Asked Questions

When should I plant Mitsuba in Glacier County, MT?

Glacier County is in Zone 4a with an average last frost of May 22. Plan your Mitsuba planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Glacier County, MT?

Glacier County, Montana is in USDA Hardiness Zone 4a. The average last spring frost is May 22 and first fall frost is September 18.

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Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Glacier County gardeners in Zone 4a organize planting dates, track what's growing, and never miss a planting window.

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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 Glacier County, MT. Local conditions may vary. Last updated: April 2026.