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When to Plant Pumpkin in Sweetwater County, WY

Sweetwater County, Wyoming Zone 4b April

Your April planting checklist for Sweetwater County, Wyoming

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

Avg. last frost May 29
Avg. first frost September 20
Soil temp (4") 16°F
Watering High
Pest pressure Low
Daylight 13.1 hrs

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Pumpkins are large-fruited squash varieties grown for eating, decoration, and seed production. They require ample space and a long, warm growing season.

Sweetwater County, Wyoming is in USDA Zone 4b. The average last spring frost is May 29 and the first fall frost is September 20, giving you a growing season of approximately 114 days.

At an elevation of 7,922 feet, Sweetwater County receives approximately 12.9 inches of rainfall annually with predominantly loam soil. Summer highs average 84°F, so choose short-season varieties of Pumpkin to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Pumpkin successfully. Mulch heavily to conserve soil moisture.

Sweetwater County, WY (Zone 4b) Short season
114 days
Last Spring Frost May 29
114 growing days
First Fall Frost September 20

Sweetwater 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
Start indoors: Apr 7 Transplant: Jun 9 🍅 Harvest: Sep 8 – Oct 27
Recommended (50%) ✗ May not fit
Start indoors: Apr 17 Transplant: Jun 19 🍅 Harvest: Sep 18 – Nov 6
Safe Start (90%) ✗ May not fit
Start indoors: May 5 Transplant: Jul 7 🍅 Harvest: Oct 6 – Nov 24

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 Sweetwater County

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

Soil pH

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

Soil Texture

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

Drainage

Drainage is adequate for Pumpkin.

Organic Matter

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

How to Plant Pumpkin

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

Plant Water Budget

Plant needs
1.3″/week
Rainfall provides
0.5″/week
You supply
1.5″/week
Watering frequency 2-3 times/week
Season total 1,479 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Pumpkin

Pumpkin needs approximately 1.3 inches of water per week (5.6" per month). Here's how your county's rainfall compares month by month.

Month Pumpkin Needs Rainfall You Supplement Action
Jan 0.8" 0" ❄️ Dormant
Feb 0.9" 0" ❄️ Dormant
Mar 1" 0" ❄️ Dormant
Apr 1.3" 0" ❄️ Dormant
May 5.6" 1.5" 4.1" 🚿 Regular watering
Jun 5.6" 1" 4.6" 🚿 Regular watering
Jul 5.6" 1.1" 4.5" 🚿 Regular watering
Aug 5.6" 1.3" 4.3" 🚿 Regular watering
Sep 5.6" 1" 4.6" 🚿 Regular watering
Oct 1.2" 0" ❄️ Dormant
Nov 1" 0" ❄️ Dormant
Dec 0.8" 0" ❄️ Dormant

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

Pumpkin 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.

Pumpkin needs ~1,332 GDD — county provides 1,482 GDD Good fit

Pumpkin Planting Timeline — Sweetwater County, WY

Pumpkin Planting Calendar

Activity When Date Range
Start Indoors April 17 Apr 17 – May 1
Transplant Outdoors June 19 Jun 19 – Jul 3
Direct Sow June 12 Jun 12 – Jul 3
Harvest September 18 Sep 18 – Nov 6

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1.3"/week · 2-3 times/week

📅 Days to Maturity

85–120 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 4b

📆 Growing Season

114 days in Sweetwater County

Growing Tips for Pumpkin in Sweetwater County

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

Your 114.0-day growing season in Sweetwater County is tight for Pumpkin (85.0-120.0 days to maturity). Start indoors and choose early-maturing varieties.

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

Sweetwater County receives only 13" of rain annually. Pumpkin needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

General growing tips

Direct sow on mounds after last frost. Allow 6-10 feet between plants. Slip a board under developing fruit to prevent rot. Harvest when rind is hard and deep in color.

Companion Planting

Good Companions

Avoid Planting Near

  • Potatoes

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Pumpkin in Sweetwater County, WY?

Sweetwater County is in Zone 4b with an average last frost of May 29. Plan your Pumpkin planting based on this frost date — see the calendar above for exact timing.

What planting zone is Sweetwater County, WY?

Sweetwater County, Wyoming is in USDA Hardiness Zone 4b. The average last spring frost is May 29 and first fall frost is September 20.

🌱

Your Sweetwater County Garden Planner — Free

A 24-page printable planner built for Sweetwater 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 Sweetwater 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.