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When to Plant Napa Cabbage in Crook County, WY

Crook County, Wyoming Zone 4b May

May to-do list for Crook County, Wyoming

May rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Crook County, Wyoming.

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. Harden off and plant napa cabbage

    Water the tray well an hour before you transplant. Roots slide out cleanly and settle in faster.

  2. Outdoor sowing time: napa cabbage

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

A few tasks this May that'll pay off in June
  • Starting indoors: napa cabbage

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Napa cabbage forms tall, barrel-shaped heads with tender, crinkled leaves and a mild, slightly sweet flavor. It is the primary cabbage used for kimchi.

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 Napa Cabbage 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
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Crook County Soil Profile

Soil Type

Loam

Soil pH

6.3-7.9

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (42 days to spare)
Start indoors: Mar 28 Transplant: May 9 🍅 Harvest: Jul 4 – Aug 8
Recommended (50%) ✓ Fits season (49 days to spare)
Start indoors: Apr 2 Transplant: May 14 🍅 Harvest: Jul 9 – Aug 13
Safe Start (90%) ✓ Fits season (48 days to spare)
Start indoors: Apr 17 Transplant: May 29 🍅 Harvest: Jul 24 – Aug 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 Crook County

How your county's soil matches Napa Cabbage's growing requirements.

Soil pH

Your soil pH (6.3–7.9) overlaps with Napa Cabbage's range (6.0–7.5), though not a perfect match.

Soil Texture

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

Organic Matter

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

How to Plant Napa Cabbage

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

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

Succession Planting Napa Cabbage

2
successive plantings in your 140-day season

Sow every 6.3 weeks. Last sowing by Jul 18 to harvest before frost.

For a dedicated fall crop, sow by Jul 09.

Plant Water Budget

Plant needs
1.5″/week
Rainfall provides
0.7″/week
You supply
0.9″/week
Watering frequency 2-3 times/week
Season total 1,130 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Napa Cabbage

Napa Cabbage needs approximately 1.5 inches of water per week (6.5" per month). Here's how your county's rainfall compares month by month.

Month Napa Cabbage 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 6.5" 3.1" 3.4" 🚿 Regular watering
Jun 6.5" 1.6" 4.9" 🚿 Regular watering
Jul 6.5" 2.1" 4.4" 🚿 Regular watering
Aug 6.5" 2.5" 4" 🚿 Regular watering
Sep 6.5" 2.2" 4.3" 🚿 Regular watering
Oct 6.5" 2.3" 4.2" 🚿 Regular 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.

Napa Cabbage 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.

Napa Cabbage needs ~748 GDD — county provides 1,610 GDD Excellent fit

Napa Cabbage Planting Timeline — Crook County, WY

Napa Cabbage 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 July 9 Jul 9 – Aug 13
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 Harvest
August Harvest
September
October
November
December
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Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

1.5"/week · 2-3 times/week

📅 Days to Maturity

55–75 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 4b

📆 Growing Season

140 days in Crook County

Growing Tips for Napa Cabbage in Crook County

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

Common pests for Napa Cabbage in this region include cabbage worm and flea beetles. Use row covers early in the season and inspect plants weekly.

Crook County receives only 25" of rain annually. Napa Cabbage needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

General growing tips

Best grown as a fall crop. Direct sow in late summer, 60-70 days before first frost. Keep soil evenly moist. Bolt-resistant varieties are available for spring planting.

Companion Planting

Good Companions

Avoid Planting Near

  • Strawberries

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Napa Cabbage in Crook County, WY?

Crook County is in Zone 4b with an average last frost of May 14. Plan your Napa Cabbage 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.

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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 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.