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When to Plant Mustard Greens in Liberty County, MT

Mustard greens are fast-growing brassicas with a spicy, peppery kick. They come in green, red, and purple varieties and are excellent cooked or in salads.

Liberty County, Montana is in USDA Zone 4a. The average last spring frost is May 26 and the first fall frost is September 15, giving you a growing season of approximately 112 days.

At an elevation of 6,728 feet, Liberty County receives approximately 18 inches of rainfall annually with predominantly loam soil. Summer highs average 83ยฐF, so choose short-season varieties of Mustard Greens to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Mustard Greens successfully. Mulch heavily to conserve soil moisture.

Liberty County, MT (Zone 4a) Short season
112 days
Last Spring Frost May 26
112 growing days
First Fall Frost September 15

Liberty County Soil Profile

Soil Type

Loam

Soil pH

6.6-7.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (15 days to spare)
Start indoors: Apr 6 Transplant: May 18 🍅 Harvest: Jun 22 – Aug 24
Recommended (50%) ✓ Fits season (14 days to spare)
Start indoors: Apr 14 Transplant: May 26 🍅 Harvest: Jun 30 – Sep 1
Safe Start (90%) ✓ Fits season (7 days to spare)
Start indoors: May 3 Transplant: Jun 14 🍅 Harvest: Jul 19 – Sep 20

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 389 gal / 100 sq ft
Drought risk

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

Mustard Greens needs ~490 GDD — county provides 1,372 GDD Excellent fit

Mustard Greens Planting Timeline โ€” Liberty County, MT

Mustard Greens Planting Calendar

Activity When Date Range
Start Indoors April 14 Apr 14 โ€“ Apr 28
Transplant Outdoors May 26 May 26 โ€“ Jun 9
Direct Sow May 19 May 19 โ€“ Jun 9
Fall Sowing June 23 Jun 23 โ€“ Jul 7
Harvest June 30 Jun 30 โ€“ Sep 1

Plant 0.5" deep ยท 6" 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 Transplant Outdoors Direct Sow Fall Sowing Harvest
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

30โ€“50 days

Soil pH

6 โ€“ 7

USDA Zone

Zone 4a

Growing Season

112 days

Growing Tips for Liberty County

Direct sow in early spring or fall. Harvest young leaves for milder flavor. Plants bolt quickly in heat so grow as a cool-season crop or provide shade.

Companion Planting

Good Companions

Avoid Planting Near

  • Strawberries

Level Up Your Garden

Frequently Asked Questions

When should I plant Mustard Greens in Liberty County, MT?

Liberty County is in Zone 4a with an average last frost of May 26. Plan your Mustard Greens planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Liberty County, MT?

Liberty County, Montana is in USDA Hardiness Zone 4a. The average last spring frost is May 26 and first fall frost is September 15.

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Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Liberty 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 Liberty County, MT. Local conditions may vary. Last updated: April 2026.