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When to Plant Mustard Greens in Valley County, ID

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.

Valley County, Idaho is in USDA Zone 4b. The average last spring frost is June 18 and the first fall frost is September 3, giving you a growing season of approximately 77 days.

At an elevation of 7,884 feet, Valley County receives approximately 17.8 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.

Valley County, ID (Zone 4b) Very short season
77 days
Last Spring Frost June 18
77 growing days
First Fall Frost September 3

Valley County Soil Profile

Soil Type

Loam

Soil pH

6.4-8.4

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Apr 30 Transplant: Jun 11 🍅 Harvest: Jul 16 – Sep 17
Recommended (50%) ✗ May not fit
Start indoors: May 7 Transplant: Jun 18 🍅 Harvest: Jul 23 – Sep 24
Safe Start (90%) ✓ Fits season (6 days to spare)
Start indoors: May 15 Transplant: Jun 26 🍅 Harvest: Jul 31 – Oct 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.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
1.0″/week
You supply
0.0″/week
Watering frequency Only during dry spells
Season total 24 gal / 100 sq ft
Drought risk

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

Mustard Greens needs ~490 GDD — county provides 943 GDD Excellent fit

Mustard Greens Planting Timeline โ€” Valley County, ID

Mustard Greens Planting Calendar

Activity When Date Range
Start Indoors May 7 May 7 โ€“ May 21
Transplant Outdoors June 18 Jun 18 โ€“ Jul 2
Direct Sow June 11 Jun 11 โ€“ Jul 2
Fall Sowing June 11 Jun 11 โ€“ Jun 25
Harvest July 23 Jul 23 โ€“ Sep 24

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

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March โ€”
April โ€”
May Start Indoors
June Transplant Outdoors Direct Sow Fall Sowing
July Transplant Outdoors Direct Sow 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 4b

Growing Season

77 days

Growing Tips for Valley 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 Valley County, ID?

Valley County is in Zone 4b with an average last frost of June 18. Plan your Mustard Greens planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Valley County, ID?

Valley County, Idaho is in USDA Hardiness Zone 4b. The average last spring frost is June 18 and first fall frost is September 3.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Valley County gardeners in Zone 4b 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 Valley County, ID. Local conditions may vary. Last updated: April 2026.