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When to Plant Garlic in Big Horn County, WY

Big Horn County, Wyoming Zone 4a April

Top priorities for Big Horn County, Wyoming gardeners in April

Each item below is timed to Big Horn County, Wyoming's frost dates and soil temperatures. Skip nothing, stress about nothing.

Avg. last frost May 9
Avg. first frost October 2
Soil temp (4") 17°F
Watering High
Pest pressure Low
Daylight 13.3 hrs

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Garlic is a pungent allium planted in fall and harvested the following summer. Hardneck varieties produce edible flower stalks (scapes) and are more cold-hardy.

Big Horn County, Wyoming is in USDA Zone 4a. The average last spring frost is May 9 and the first fall frost is October 2, giving you a growing season of approximately 146 days.

At an elevation of 7,668 feet, Big Horn County receives approximately 13.7 inches of rainfall annually with predominantly loam soil. Summer highs average 84°F, so choose short-season varieties of Garlic to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Garlic successfully. Mulch heavily to conserve soil moisture.

Big Horn County, WY (Zone 4a) Short season
146 days
Last Spring Frost May 9
146 growing days
First Fall Frost October 2

Big Horn County Soil Profile

Soil Type

Loam

Soil pH

6.2-7.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Transplant: May 4 🍅 Harvest: Aug 3 – Sep 28
Recommended (50%) ✗ May not fit
Transplant: May 9 🍅 Harvest: Aug 8 – Oct 3
Safe Start (90%) ✓ Fits season (2 days to spare)
Transplant: May 19 🍅 Harvest: Aug 18 – Oct 13

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 Big Horn County

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

Soil pH

Your soil pH (6.2–7.7) overlaps with Garlic's range (6.0–7.5), though not a perfect match.

Soil Texture

The loam soil in Big Horn County is excellent for Garlic — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (2.9%). Annual compost additions will help Garlic.

How to Plant Garlic

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

Fall planting: Sow 6 weeks before your first frost date for a fall harvest.

Plant Water Budget

Plant needs
0.5″/week
Rainfall provides
0.4″/week
You supply
0.1″/week
Watering frequency Only during dry spells
Season total 165 gal / 100 sq ft
Drought risk

Water stress score is 8/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Garlic

Garlic needs approximately 0.5 inches of water per week (2.2" per month). Here's how your county's rainfall compares month by month.

Month Garlic Needs Rainfall You Supplement Action
Jan 0.9" 0" ❄️ Dormant
Feb 0.8" 0" ❄️ Dormant
Mar 1.2" 0" ❄️ Dormant
Apr 1.4" 0" ❄️ Dormant
May 2.2" 1.6" 0.6" 💧 Light watering
Jun 2.2" 0.9" 1.3" 🚿 Regular watering
Jul 2.2" 1.4" 0.8" 💧 Light watering
Aug 2.2" 1.6" 0.6" 💧 Light watering
Sep 2.2" 1.2" 1" 💧 Light watering
Oct 2.2" 1.2" 1" 💧 Light watering
Nov 0.8" 0" ❄️ Dormant
Dec 0.8" 0" ❄️ Dormant

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

Garlic 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.

Garlic needs ~2,145 GDD — county provides 1,898 GDD May not mature

Garlic Planting Timeline — Big Horn County, WY

Garlic Planting Calendar

Activity When Date Range
Fall Sowing August 21 Aug 21 – Sep 4

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

Month-by-Month Timeline

MonthActivities
January
February
March
April
May
June
July
August Fall Sowing
September Fall Sowing
October
November
December

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.5"/week · Only during dry spells

📅 Days to Maturity

90–240 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 4a

📆 Growing Season

146 days in Big Horn County

Growing Tips for Garlic in Big Horn County

Direct sow Garlic outdoors after May 09 in Big Horn County when soil has warmed and frost danger has passed.

Your 146.0-day growing season in Big Horn County is tight for Garlic (90.0-240.0 days to maturity). Start indoors and choose early-maturing varieties.

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

General growing tips

Plant individual cloves pointed end up in fall, 6 weeks before ground freezes. Mulch heavily with straw. Harvest when lower leaves begin to brown but 5-6 green leaves remain.

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 Garlic in Big Horn County, WY?

Big Horn County is in Zone 4a with an average last frost of May 9. Plan your Garlic planting based on this frost date — see the calendar above for exact timing.

What planting zone is Big Horn County, WY?

Big Horn County, Wyoming is in USDA Hardiness Zone 4a. The average last spring frost is May 9 and first fall frost is October 2.

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Your Big Horn County Garden Planner — Free

A 24-page printable planner built for Big Horn County (Zone 4a). 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 Big Horn County, WY. Local conditions may vary. Last updated: April 2026.

Sources & credits

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