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When to Plant Onion in Wayne County, UT

Onions are a fundamental kitchen staple available in yellow, white, and red varieties. Choose long-day, short-day, or intermediate types based on your latitude.

Wayne County, Utah is in USDA Zone 5b. The average last spring frost is May 14 and the first fall frost is October 2, giving you a growing season of approximately 141 days.

At an elevation of 7,565 feet, Wayne County receives approximately 22.8 inches of rainfall annually with predominantly loam soil. Summer highs average 86ยฐF, providing good warmth for Onion during the growing season.

Wayne County, UT (Zone 5b) Short season
141 days
Last Spring Frost May 14
141 growing days
First Fall Frost October 2

Wayne County Soil Profile

Soil Type

Loam

Soil pH

6.2-7.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (6 days to spare)
Start indoors: Mar 27 Transplant: May 1 🍅 Harvest: Jul 31 – Sep 18
Recommended (50%) ✓ Fits season (1 days to spare)
Start indoors: Apr 9 Transplant: May 14 🍅 Harvest: Aug 13 – Oct 1
Safe Start (90%) ✗ May not fit
Start indoors: May 3 Transplant: Jun 7 🍅 Harvest: Sep 6 – Oct 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
0.7″/week
You supply
0.4″/week
Watering frequency 1-2 times/week
Season total 483 gal / 100 sq ft
Drought risk

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

Onion needs ~1,522 GDD — county provides 2,044 GDD Excellent fit

Onion Planting Timeline โ€” Wayne County, UT

Onion Planting Calendar

Activity When Date Range
Start Indoors April 9 Apr 9 โ€“ Apr 23
Transplant Outdoors May 14 May 14 โ€“ May 28
Direct Sow April 30 Apr 30 โ€“ May 21
Fall Sowing July 24 Jul 24 โ€“ Aug 7
Harvest August 13 Aug 13 โ€“ Oct 1

Plant 1" deep ยท 6" apart ยท Rows 12" apart

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March โ€”
April Start Indoors Direct Sow
May Transplant Outdoors Direct Sow
June โ€”
July Fall Sowing
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€“120 days

Soil pH

6 โ€“ 7

USDA Zone

Zone 5b

Growing Season

141 days

Growing Tips for Wayne County

Start seeds indoors 8-10 weeks before transplanting. Match day-length type to your latitude. Stop watering when tops begin to fall over and cure bulbs for 2-3 weeks before storage.

Companion Planting

Good Companions

Avoid Planting Near

  • Peas
  • Green Beans
  • Asparagus

Level Up Your Garden

Frequently Asked Questions

When should I plant Onion in Wayne County, UT?

Wayne County is in Zone 5b with an average last frost of May 14. Plan your Onion planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Wayne County, UT?

Wayne County, Utah is in USDA Hardiness Zone 5b. The average last spring frost is May 14 and first fall frost is October 2.

๐ŸŒฑ

Plan Your Garden with Confidence

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