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When to Plant Leeks in Crook County, WY

Crook County, Wyoming Zone 4b May

This month in Crook County, Wyoming

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

Avg. last frost May 14
Avg. first frost October 1
Soil temp (4") 31°F
Watering Moderate
Pest pressure Low
Daylight 14.6 hrs
  1. Plant out leeks

    Your last frost (May 14) has passed. These warm-season crops can handle outdoor soil now.

  2. Plant leeks from seed, right in the garden

    Thin ruthlessly once seedlings are up. Crowded roots mean smaller crops from every plant.

June will be here before you know it — start on
  • Starting indoors: leeks

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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.

Crook County, Wyoming is in USDA Zone 4b. The average last spring frost is May 14 and the first fall frost is October 1, giving you a growing season of approximately 140 days.

At an elevation of 8,060 feet, Crook County receives approximately 24.8 inches of rainfall annually with predominantly loam soil. Summer highs average 82°F, so choose short-season varieties of Leeks to ensure they mature before fall.

Crook County, WY (Zone 4b) Short season
140 days
Last Spring Frost May 14
140 growing days
First Fall Frost October 1

Crook County Soil Profile

Soil Type

Loam

Soil pH

6.3-7.9

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Mar 28 Transplant: May 9 🍅 Harvest: Aug 8 – Oct 3
Recommended (50%) ✗ May not fit
Start indoors: Apr 2 Transplant: May 14 🍅 Harvest: Aug 13 – Oct 8
Safe Start (90%) ✗ May not fit
Start indoors: Apr 17 Transplant: May 29 🍅 Harvest: Aug 28 – Oct 23

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 Crook County

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

Soil pH

Your soil pH (6.3–7.9) is more alkaline than Leeks prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.4%). Annual compost additions will help Leeks.

How to Plant Leeks

1"
Planting Depth
15"
Between Plants
24"
Between Rows

Fall planting: Sow 12 weeks before your first frost date for a fall harvest.

Plant Water Budget

Plant needs
0.8″/week
Rainfall provides
0.7″/week
You supply
0.1″/week
Watering frequency Only during dry spells
Season total 84 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Leeks

Leeks needs approximately 0.8 inches of water per week (3.5" per month). Here's how your county's rainfall compares month by month.

Month Leeks Needs Rainfall You Supplement Action
Jan 1.6" 0" ❄️ Dormant
Feb 1.5" 0" ❄️ Dormant
Mar 1.9" 0" ❄️ Dormant
Apr 2.9" 0" ❄️ Dormant
May 3.5" 3.1" 0.4" 💧 Light watering
Jun 3.5" 1.6" 1.9" 🚿 Regular watering
Jul 3.5" 2.1" 1.4" 💧 Light watering
Aug 3.5" 2.5" 1" 💧 Light watering
Sep 3.5" 2.2" 1.3" 💧 Light watering
Oct 3.5" 2.3" 1.2" 💧 Light watering
Nov 1.6" 0" ❄️ Dormant
Dec 1.5" 0" ❄️ Dormant

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

Leeks 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.

Leeks needs ~1,380 GDD — county provides 1,610 GDD Good fit

Leeks Planting Timeline — Crook County, WY

Leeks Planting Calendar

Activity When Date Range
Start Indoors April 2 Apr 2 – Apr 16
Transplant Outdoors May 14 May 14 – May 28
Direct Sow May 7 May 7 – May 28
Harvest August 13 Aug 13 – Oct 8
Fall Sowing July 9 Jul 9 – Jul 23

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.8"/week · Only during dry spells

📅 Days to Maturity

90–150 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 4b

📆 Growing Season

140 days in Crook County

Growing Tips for Leeks in Crook County

Direct sow Leeks outdoors after May 14 in Crook County when soil has warmed and frost danger has passed.

Your 140.0-day growing season in Crook County is tight for Leeks (90.0-150.0 days to maturity). Start indoors and choose early-maturing varieties.

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

General growing tips

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

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Leeks in Crook County, WY?

Crook County is in Zone 4b with an average last frost of May 14. Plan your Leeks planting based on this frost date — see the calendar above for exact timing.

What planting zone is Crook County, WY?

Crook County, Wyoming is in USDA Hardiness Zone 4b. The average last spring frost is May 14 and first fall frost is October 1.

🌱

Your Crook County Garden Planner — Free

A 24-page printable planner built for Crook County (Zone 4b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

Instant PDF download. No spam, unsubscribe any time.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Crook 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.