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When to Plant Kohlrabi in Iron County, UT

Kohlrabi is an unusual brassica that forms a swollen stem above ground with a mild, sweet turnip-like flavor. Both the bulb and tender leaves are edible.

Iron County, Utah is in USDA Zone 6b. The average last spring frost is May 21 and the first fall frost is October 1, giving you a growing season of approximately 133 days.

At an elevation of 6,296 feet, Iron County receives approximately 20 inches of rainfall annually with predominantly loam soil. Summer highs average 86ยฐF, providing good warmth for Kohlrabi during the growing season.

Iron County, UT (Zone 6b) Short season
133 days
Last Spring Frost May 21
133 growing days
First Fall Frost October 1

Iron County Soil Profile

Soil Type

Loam

Soil pH

6.4-7.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (50 days to spare)
Start indoors: Apr 8 Transplant: May 13 🍅 Harvest: Jul 1 – Aug 5
Recommended (50%) ✓ Fits season (49 days to spare)
Start indoors: Apr 16 Transplant: May 21 🍅 Harvest: Jul 9 – Aug 13
Safe Start (90%) ✓ Fits season (45 days to spare)
Start indoors: May 5 Transplant: Jun 9 🍅 Harvest: Jul 28 – Sep 1

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
0.4″/week
Watering frequency 1-2 times/week
Season total 523 gal / 100 sq ft
Drought risk

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

Kohlrabi needs ~798 GDD — county provides 1,928 GDD Excellent fit

Kohlrabi Planting Timeline โ€” Iron County, UT

Kohlrabi Planting Calendar

Activity When Date Range
Start Indoors April 16 Apr 16 โ€“ Apr 30
Transplant Outdoors May 21 May 21 โ€“ Jun 4
Direct Sow May 7 May 7 โ€“ May 28
Fall Sowing July 23 Jul 23 โ€“ Aug 6
Harvest July 9 Jul 9 โ€“ Aug 13

Plant 0.5" deep ยท 4" 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
July Fall Sowing Harvest
August Fall Sowing Harvest
September โ€”
October โ€”
November โ€”
December โ€”

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Moderate โ€” regular watering

Days to Maturity

45โ€“65 days

Soil pH

6 โ€“ 7.5

USDA Zone

Zone 6b

Growing Season

133 days

Growing Tips for Iron County

Direct sow in spring or fall. Harvest when bulbs are 2-3 inches in diameter for best texture and flavor. Larger bulbs may become woody and fibrous.

Companion Planting

Good Companions

Avoid Planting Near

  • Tomatoes
  • Strawberries

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Frequently Asked Questions

When should I plant Kohlrabi in Iron County, UT?

Iron County is in Zone 6b with an average last frost of May 21. Plan your Kohlrabi planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Iron County, UT?

Iron County, Utah is in USDA Hardiness Zone 6b. The average last spring frost is May 21 and first fall frost is October 1.

๐ŸŒฑ

Plan Your Garden with Confidence

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