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When to Plant Mustard Greens in Clearwater 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.

Clearwater County, Idaho is in USDA Zone 5b. The average last spring frost is May 17 and the first fall frost is September 28, giving you a growing season of approximately 134 days.

At an elevation of 7,800 feet, Clearwater County receives approximately 19 inches of rainfall annually with predominantly loam soil. Summer highs average 87ยฐF, providing good warmth for Mustard Greens during the growing season. With low rainfall, drip irrigation is essential for growing Mustard Greens successfully. Mulch heavily to conserve soil moisture.

Clearwater County, ID (Zone 5b) Short season
134 days
Last Spring Frost May 17
134 growing days
First Fall Frost September 28

Clearwater County Soil Profile

Soil Type

Loam

Soil pH

6.5-8.1

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (36 days to spare)
Start indoors: Apr 3 Transplant: May 8 🍅 Harvest: Jun 12 – Aug 14
Recommended (50%) ✓ Fits season (36 days to spare)
Start indoors: Apr 12 Transplant: May 17 🍅 Harvest: Jun 21 – Aug 23
Safe Start (90%) ✓ Fits season (43 days to spare)
Start indoors: May 6 Transplant: Jun 10 🍅 Harvest: Jul 15 – Sep 16

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
0.6″/week
You supply
0.5″/week
Watering frequency 1-2 times/week
Season total 579 gal / 100 sq ft
Drought risk

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

Mustard Greens needs ~610 GDD — county provides 2,043 GDD Excellent fit

Mustard Greens Planting Timeline โ€” Clearwater County, ID

Mustard Greens Planting Calendar

Activity When Date Range
Start Indoors April 12 Apr 12 โ€“ Apr 26
Transplant Outdoors May 17 May 17 โ€“ May 31
Direct Sow May 3 May 3 โ€“ May 24
Fall Sowing July 20 Jul 20 โ€“ Aug 3
Harvest June 21 Jun 21 โ€“ Aug 23

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 Harvest
July Fall Sowing Harvest
August Fall Sowing Harvest
September โ€”
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 5b

Growing Season

134 days

Growing Tips for Clearwater 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 Clearwater County, ID?

Clearwater County is in Zone 5b with an average last frost of May 17. Plan your Mustard Greens planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Clearwater County, ID?

Clearwater County, Idaho is in USDA Hardiness Zone 5b. The average last spring frost is May 17 and first fall frost is September 28.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Clearwater County gardeners in Zone 5b organize planting dates, track what's growing, and never miss a planting window.

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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 Clearwater County, ID. Local conditions may vary. Last updated: April 2026.