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When to Plant Onion in Albany County, WY

Albany County, Wyoming Zone 5b May

What to do in May

We've pulled the most time-sensitive tasks for Albany County, Wyoming this May and put them front and centre. Tackle them in order.

Avg. last frost May 29
Avg. first frost September 18
Soil temp (4") 38°F
Watering High
Pest pressure Low
Daylight 14.3 hrs
  1. Transplant onion outside

    Plant tomatoes deep — bury the stem up to the first true leaves to grow extra roots. Everything else goes in at the same depth it grew in the tray.

  2. Scatter onion into prepared beds

    Sow every 2 weeks for a continuous harvest. A single big planting means a single big glut.

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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.

Albany County, Wyoming is in USDA Zone 5b. The average last spring frost is May 29 and the first fall frost is September 18, giving you a growing season of approximately 112 days.

At an elevation of 5,863 feet, Albany County receives approximately 17.8 inches of rainfall annually with predominantly loam soil. Summer highs average 80°F, so choose short-season varieties of Onion to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Onion successfully. Mulch heavily to conserve soil moisture.

Albany County, WY (Zone 5b) Short season
112 days
Last Spring Frost May 29
112 growing days
First Fall Frost September 18
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Albany County Soil Profile

Soil Type

Loam

Soil pH

6.3-7.6

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Apr 19 Transplant: May 24 🍅 Harvest: Aug 23 – Oct 11
Recommended (50%) ✗ May not fit
Start indoors: Apr 24 Transplant: May 29 🍅 Harvest: Aug 28 – Oct 16
Safe Start (90%) ✗ May not fit
Start indoors: May 6 Transplant: Jun 10 🍅 Harvest: Sep 9 – Oct 28

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.

Soil Compatibility in Albany County

How your county's soil matches Onion's growing requirements.

Soil pH

Your soil pH (6.3–7.6) overlaps with Onion's range (6.0–7.0), though not a perfect match.

Soil Texture

The loam soil in Albany County is excellent for Onion — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (2.5%). Annual compost additions will help Onion.

How to Plant Onion

1"
Planting Depth
6"
Between Plants
12"
Between Rows

Fall planting: Sow 10 weeks before your first frost date for a fall harvest.

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 398 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Onion

Onion needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Onion Needs Rainfall You Supplement Action
Jan 1.1" 0" ❄️ Dormant
Feb 1.2" 0" ❄️ Dormant
Mar 1.5" 0" ❄️ Dormant
Apr 1.8" 0" ❄️ Dormant
May 4.3" 2.2" 2.1" 💧 Light watering
Jun 4.3" 1.2" 3.1" 🚿 Regular watering
Jul 4.3" 1.4" 2.9" 🚿 Regular watering
Aug 4.3" 2" 2.3" 🚿 Regular watering
Sep 4.3" 1.3" 3" 🚿 Regular watering
Oct 1.6" 0" ❄️ Dormant
Nov 1.4" 0" ❄️ Dormant
Dec 1.1" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Albany County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Onion Heat Requirements (GDD)

What are Growing Degree Days (GDD)?

Growing Degree Days measure the total warmth your plants receive during the growing season. Think of it as a "heat bank" — every day above 50°F deposits warmth that helps your plants grow.

Each plant needs a certain amount of accumulated heat to mature. If your county provides more GDD than the plant needs, it's a great fit. If it's close, you may want to choose faster-maturing varieties or start seeds indoors to get a head start.

Onion needs ~1,050 GDD — county provides 1,120 GDD Good fit

Onion Planting Timeline — Albany County, WY

Onion Planting Calendar

Activity When Date Range
Start Indoors April 24 Apr 24 – May 8
Transplant Outdoors May 29 May 29 – Jun 12
Direct Sow May 15 May 15 – Jun 5
Harvest August 28 Aug 28 – Oct 16
Fall Sowing July 10 Jul 10 – Jul 24

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

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · 1-2 times/week

📅 Days to Maturity

90–120 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 5b

📆 Growing Season

112 days in Albany County

Growing Tips for Onion in Albany County

Direct sow Onion outdoors after May 29 in Albany County when soil has warmed and frost danger has passed.

Your 112.0-day growing season in Albany County is tight for Onion (90.0-120.0 days to maturity). Start indoors and choose early-maturing varieties.

Common pests for Onion in this region include onion maggots and thrips. Use row covers early in the season and inspect plants weekly.

Albany County receives only 18" of rain annually. Onion needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

General growing tips

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

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Onion in Albany County, WY?

Albany County is in Zone 5b with an average last frost of May 29. Plan your Onion planting based on this frost date — see the calendar above for exact timing.

What planting zone is Albany County, WY?

Albany County, Wyoming is in USDA Hardiness Zone 5b. The average last spring frost is May 29 and first fall frost is September 18.

🌱

Your Albany County Garden Planner — Free

A 24-page printable planner built for Albany County (Zone 5b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

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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 Albany County, WY. Local conditions may vary. Last updated: May 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.