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When to Plant Leeks in Utah County, UT

Leeks are a mild, sweet allium that produces long white shanks. They are more refined than onions and are a key ingredient in soups, stews, and gratins.

Utah County, Utah is in USDA Zone 6a. The average last spring frost is May 5 and the first fall frost is October 11, giving you a growing season of approximately 159 days.

At an elevation of 5,535 feet, Utah County receives approximately 22.1 inches of rainfall annually with predominantly loam soil. Summer highs average 86ยฐF, providing good warmth for Leeks during the growing season.

Utah County, UT (Zone 6a) Moderate season
159 days
Last Spring Frost May 5
159 growing days
First Fall Frost October 11

Utah County Soil Profile

Soil Type

Loam

Soil pH

6.5-8.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Mar 22 Transplant: Apr 26 🍅 Harvest: Jul 26 – Oct 11
Recommended (50%) ✗ May not fit
Start indoors: Mar 31 Transplant: May 5 🍅 Harvest: Aug 4 – Oct 20
Safe Start (90%) ✗ May not fit
Start indoors: Apr 26 Transplant: May 31 🍅 Harvest: Aug 30 – Nov 15

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 707 gal / 100 sq ft
Drought risk

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

Leeks needs ~1,740 GDD — county provides 2,305 GDD Excellent fit

Leeks Planting Timeline โ€” Utah County, UT

Leeks Planting Calendar

Activity When Date Range
Start Indoors March 31 Mar 31 โ€“ Apr 14
Transplant Outdoors May 5 May 5 โ€“ May 19
Direct Sow April 21 Apr 21 โ€“ May 12
Fall Sowing August 2 Aug 2 โ€“ Aug 16
Harvest August 4 Aug 4 โ€“ Oct 20

Plant 1" deep ยท 15" apart ยท Rows 24" apart

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March Start Indoors
April Start Indoors Direct Sow
May Transplant Outdoors Direct Sow
June โ€”
July โ€”
August Fall Sowing Harvest
September Harvest
October Harvest
November โ€”
December โ€”

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Moderate โ€” regular watering

Days to Maturity

90โ€“150 days

Soil pH

6 โ€“ 7

USDA Zone

Zone 6a

Growing Season

159 days

Growing Tips for Utah County

Start seeds indoors 10-12 weeks before last frost. Transplant into trenches and hill soil around stems as they grow to increase the white portion. Harvest as needed.

Companion Planting

Good Companions

Avoid Planting Near

  • Peas
  • Green Beans

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Frequently Asked Questions

When should I plant Leeks in Utah County, UT?

Utah County is in Zone 6a with an average last frost of May 5. Plan your Leeks planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Utah County, UT?

Utah County, Utah is in USDA Hardiness Zone 6a. The average last spring frost is May 5 and first fall frost is October 11.

๐ŸŒฑ

Plan Your Garden with Confidence

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