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When to Plant Mustard Greens in Navajo County, AZ

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.

Navajo County, Arizona is in USDA Zone 6a. The average last spring frost is May 2 and the first fall frost is October 16, giving you a growing season of approximately 167 days.

At an elevation of 5,528 feet, Navajo County receives approximately 15.8 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 94ยฐF, providing good warmth for Mustard Greens during the growing season. Sandy soil warms quickly in spring โ€” great for early planting โ€” but Mustard Greens will need more frequent watering and organic matter to retain nutrients. With low rainfall, drip irrigation is essential for growing Mustard Greens successfully. Mulch heavily to conserve soil moisture.

Navajo County, AZ (Zone 6a) Moderate season
167 days
Last Spring Frost May 2
167 growing days
First Fall Frost October 16

Navajo County Soil Profile

Soil Type

Sandy Loam

Soil pH

7.3-8.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (70 days to spare)
Start indoors: Mar 21 Transplant: Apr 25 🍅 Harvest: May 30 – Aug 1
Recommended (50%) ✓ Fits season (69 days to spare)
Start indoors: Mar 28 Transplant: May 2 🍅 Harvest: Jun 6 – Aug 8
Safe Start (90%) ✓ Fits season (68 days to spare)
Start indoors: Apr 13 Transplant: May 18 🍅 Harvest: Jun 22 – Aug 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
0.4″/week
You supply
1.1″/week
Watering frequency 2-3 times/week
Season total 1,610 gal / 100 sq ft
Drought risk

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

Mustard Greens needs ~820 GDD — county provides 3,423 GDD Excellent fit

Mustard Greens Planting Timeline โ€” Navajo County, AZ

Mustard Greens Planting Calendar

Activity When Date Range
Start Indoors March 28 Mar 28 โ€“ Apr 11
Transplant Outdoors May 2 May 2 โ€“ May 16
Direct Sow April 18 Apr 18 โ€“ May 9
Fall Sowing August 7 Aug 7 โ€“ Aug 21
Harvest June 6 Jun 6 โ€“ Aug 8

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

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March Start Indoors
April Start Indoors Direct Sow
May Transplant Outdoors Direct Sow
June Harvest
July 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 6a

Growing Season

167 days

Growing Tips for Navajo 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 Navajo County, AZ?

Navajo County is in Zone 6a with an average last frost of May 2. Plan your Mustard Greens planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Navajo County, AZ?

Navajo County, Arizona is in USDA Hardiness Zone 6a. The average last spring frost is May 2 and first fall frost is October 16.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Navajo County gardeners in Zone 6a 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 Navajo County, AZ. Local conditions may vary. Last updated: April 2026.