Blog

When to Plant Mitsuba in Beaverhead 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.

Beaverhead County, Montana is in USDA Zone 4a. The average last spring frost is June 10 and the first fall frost is September 12, giving you a growing season of approximately 94 days.

At an elevation of 7,645 feet, Beaverhead County receives approximately 15.7 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.

Beaverhead County, MT (Zone 4a) Very short season
94 days
Last Spring Frost June 10
94 growing days
First Fall Frost September 12

Beaverhead County Soil Profile

Soil Type

Loam

Soil pH

6.8-7.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Apr 19 Transplant: May 24 🍅 Harvest: Jul 19 – Sep 13
Recommended (50%) ✗ May not fit
Start indoors: Apr 29 Transplant: Jun 3 🍅 Harvest: Jul 29 – Sep 23
Safe Start (90%) ✗ May not fit
Start indoors: May 11 Transplant: Jun 15 🍅 Harvest: Aug 10 – Oct 5

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
0.7″/week
You supply
0.4″/week
Watering frequency 1-2 times/week
Season total 300 gal / 100 sq ft
Drought risk

Water stress score is 6/10 โ€” consider drought-tolerant varieties and mulching

Mitsuba needs ~600 GDD — county provides 940 GDD Excellent fit

Mitsuba Planting Timeline โ€” Beaverhead County, MT

Mitsuba Planting Calendar

Activity When Date Range
Start Indoors April 29 Apr 29 โ€“ May 13
Transplant Outdoors June 3 Jun 3 โ€“ Jun 17
Direct Sow June 3 Jun 3 โ€“ Jun 24
Fall Sowing June 20 Jun 20 โ€“ Jul 4
Harvest July 29 Jul 29 โ€“ Sep 23

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 Start Indoors
June Transplant Outdoors 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

94 days

Growing Tips for Beaverhead 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 Beaverhead County, MT?

Beaverhead County is in Zone 4a with an average last frost of June 10. Plan your Mitsuba planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Beaverhead County, MT?

Beaverhead County, Montana is in USDA Hardiness Zone 4a. The average last spring frost is June 10 and first fall frost is September 12.

๐ŸŒฑ

Plan Your Garden with Confidence

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

Get Your Free Garden Planner →

Free download. Plan your entire garden season in minutes.

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