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When to Plant Leeks in Sanpete 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.

Sanpete County, Utah is in USDA Zone 5b. The average last spring frost is May 21 and the first fall frost is September 28, giving you a growing season of approximately 130 days.

At an elevation of 6,969 feet, Sanpete County receives approximately 14.2 inches of rainfall annually with predominantly loam soil. Summer highs average 86ยฐF, providing good warmth for Leeks during the growing season. With low rainfall, drip irrigation is essential for growing Leeks successfully. Mulch heavily to conserve soil moisture.

Sanpete County, UT (Zone 5b) Short season
130 days
Last Spring Frost May 21
130 growing days
First Fall Frost September 28

Sanpete County Soil Profile

Soil Type

Loam

Soil pH

6.5-7.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Apr 8 Transplant: May 13 🍅 Harvest: Aug 12 – Oct 28
Recommended (50%) ✗ May not fit
Start indoors: Apr 16 Transplant: May 21 🍅 Harvest: Aug 20 – Nov 5
Safe Start (90%) ✗ May not fit
Start indoors: May 6 Transplant: Jun 10 🍅 Harvest: Sep 9 – Nov 25

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
0.5″/week
You supply
0.7″/week
Watering frequency 1-2 times/week
Season total 751 gal / 100 sq ft
Drought risk

Water stress score is 6/10 โ€” consider drought-tolerant varieties and mulching

Leeks needs ~1,740 GDD — county provides 1,885 GDD Good fit

Leeks Planting Timeline โ€” Sanpete County, UT

Leeks 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 20 Jul 20 โ€“ Aug 3
Harvest August 20 Aug 20 โ€“ Nov 5

Plant 1" deep ยท 15" apart ยท Rows 24" 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
August Fall Sowing Harvest
September Harvest
October Harvest
November Harvest
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 5b

Growing Season

130 days

Growing Tips for Sanpete 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

Level Up Your Garden

Frequently Asked Questions

When should I plant Leeks in Sanpete County, UT?

Sanpete County is in Zone 5b with an average last frost of May 21. Plan your Leeks planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Sanpete County, UT?

Sanpete County, Utah is in USDA Hardiness Zone 5b. The average last spring frost is May 21 and first fall frost is September 28.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Sanpete County gardeners in Zone 5b 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 Sanpete County, UT. Local conditions may vary. Last updated: April 2026.