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When to Plant Butternut Squash in Johnson County, WY

Johnson County, Wyoming Zone 5a May

Your May game plan for Johnson County, Wyoming

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

Avg. last frost May 17
Avg. first frost September 21
Soil temp (4") 30°F
Watering Moderate
Pest pressure Low
Daylight 14.6 hrs
  1. Transplant butternut squash outside

    Harden off for 7 days — a little more sun each day — before planting. That's the difference between a seedling that thrives and one that stalls.

  2. Put butternut squash seeds straight in the ground

    Keep the top inch of soil moist until germination — a gentle morning watering for 5–7 days does the job.

Looking ahead to June
  • Starting indoors: butternut squash

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Butternut squash is a popular winter squash with a long neck, small seed cavity, and sweet, nutty orange flesh. It stores exceptionally well for months.

Johnson County, Wyoming is in USDA Zone 5a. The average last spring frost is May 17 and the first fall frost is September 21, giving you a growing season of approximately 127 days.

At an elevation of 8,281 feet, Johnson County receives approximately 23.7 inches of rainfall annually with predominantly loam soil. Summer highs average 81°F, so choose short-season varieties of Butternut Squash to ensure they mature before fall.

Johnson County, WY (Zone 5a) Short season
127 days
Last Spring Frost May 17
127 growing days
First Fall Frost September 21
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Johnson County Soil Profile

Soil Type

Loam

Soil pH

6.8-7.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Apr 8 Transplant: May 27 🍅 Harvest: Aug 26 – Sep 30
Recommended (50%) ✗ May not fit
Start indoors: Apr 12 Transplant: May 31 🍅 Harvest: Aug 30 – Oct 4
Safe Start (90%) ✗ May not fit
Start indoors: May 3 Transplant: Jun 21 🍅 Harvest: Sep 20 – 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.

Soil Compatibility in Johnson County

How your county's soil matches Butternut Squash's growing requirements.

Soil pH

Your soil pH (6.8–7.8) is more alkaline than Butternut Squash prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

The loam soil in Johnson County is excellent for Butternut Squash — good drainage, moisture retention, and nutrient holding capacity.

Drainage

Drainage is adequate for Butternut Squash.

Organic Matter

Organic matter is moderate (2.2%). Annual compost additions will help Butternut Squash.

How to Plant Butternut Squash

1"
Planting Depth
30"
Between Plants
42"
Between Rows

Plant Water Budget

Plant needs
1.1″/week
Rainfall provides
0.8″/week
You supply
0.8″/week
Watering frequency 2-3 times/week
Season total 877 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Butternut Squash

Butternut Squash needs approximately 1.1 inches of water per week (4.8" per month). Here's how your county's rainfall compares month by month.

Month Butternut Squash Needs Rainfall You Supplement Action
Jan 1.8" 0" ❄️ Dormant
Feb 1.5" 0" ❄️ Dormant
Mar 1.9" 0" ❄️ Dormant
Apr 2.1" 0" ❄️ Dormant
May 4.8" 2.8" 2" 💧 Light watering
Jun 4.8" 1.6" 3.2" 🚿 Regular watering
Jul 4.8" 2.3" 2.5" 🚿 Regular watering
Aug 4.8" 2.5" 2.3" 💧 Light watering
Sep 4.8" 2.1" 2.7" 🚿 Regular watering
Oct 2.1" 0" ❄️ Dormant
Nov 1.5" 0" ❄️ Dormant
Dec 1.5" 0" ❄️ Dormant

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

Butternut Squash 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.

Butternut Squash needs ~1,048 GDD — county provides 1,365 GDD Excellent fit

Butternut Squash Planting Timeline — Johnson County, WY

Butternut Squash Planting Calendar

Activity When Date Range
Start Indoors April 12 Apr 12 – Apr 26
Transplant Outdoors May 31 May 31 – Jun 14
Direct Sow May 24 May 24 – Jun 14
Harvest August 30 Aug 30 – Oct 4

Plant 1" deep · 30" apart · Rows 42" apart

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1.1"/week · 2-3 times/week

📅 Days to Maturity

85–110 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 5a

📆 Growing Season

127 days in Johnson County

Growing Tips for Butternut Squash in Johnson County

Direct sow Butternut Squash outdoors after May 17 in Johnson County when soil has warmed and frost danger has passed.

Common pests for Butternut Squash in this region include squash vine borer and cucumber beetles. Use row covers early in the season and inspect plants weekly.

Johnson County receives only 24" of rain annually. Butternut Squash needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

General growing tips

Start seeds indoors 3 weeks early or direct sow after frost. Allow 6-8 feet for sprawling vines. Harvest when the skin is hard and uniformly tan. Cure in the sun for 10 days.

Companion Planting

Good Companions

Avoid Planting Near

  • Potatoes

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Butternut Squash in Johnson County, WY?

Johnson County is in Zone 5a with an average last frost of May 17. Plan your Butternut Squash planting based on this frost date — see the calendar above for exact timing.

What planting zone is Johnson County, WY?

Johnson County, Wyoming is in USDA Hardiness Zone 5a. The average last spring frost is May 17 and first fall frost is September 21.

🌱

Your Johnson County Garden Planner — Free

A 24-page printable planner built for Johnson County (Zone 5a). 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 Johnson 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.