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When to Plant Acorn Squash in Larimer County, CO

Larimer County, Colorado Zone 5b May

Your May game plan for Larimer County, Colorado

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

Avg. last frost May 2
Avg. first frost October 6
Soil temp (4") 36°F
Watering High
Pest pressure Low
Daylight 14.3 hrs
  1. Move acorn squash into the garden

    Frost risk is low now in Larimer County, Colorado. If you've been covering beds overnight, you can stop.

  2. Seed acorn squash outdoors

    Rake a smooth bed, make a shallow furrow, drop seeds at the spacing on the packet, water gently, walk away.

Get ahead of June
  • Starting indoors: acorn squash

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Acorn squash is a small winter squash with dark green, ribbed skin and mildly sweet orange flesh. It is perfect for stuffing and roasting as individual servings.

Larimer County, Colorado is in USDA Zone 5b. The average last spring frost is May 2 and the first fall frost is October 6, giving you a growing season of approximately 157 days.

At an elevation of 7,108 feet, Larimer County receives approximately 23.4 inches of rainfall annually with predominantly loam soil. Summer highs average 84°F, so choose short-season varieties of Acorn Squash to ensure they mature before fall.

Larimer County, CO (Zone 5b) Moderate season
157 days
Last Spring Frost May 2
157 growing days
First Fall Frost October 6
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Larimer County Soil Profile

Soil Type

Loam

Soil pH

6.4-8.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (23 days to spare)
Start indoors: Mar 24 Transplant: May 12 🍅 Harvest: Aug 4 – Sep 8
Recommended (50%) ✓ Fits season (24 days to spare)
Start indoors: Mar 28 Transplant: May 16 🍅 Harvest: Aug 8 – Sep 12
Safe Start (90%) ✓ Fits season (19 days to spare)
Start indoors: Apr 16 Transplant: Jun 4 🍅 Harvest: Aug 27 – Oct 1

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 Larimer County

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

Soil pH

Your soil pH (6.4–8.2) is more alkaline than Acorn Squash prefers (5.5–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Drainage

Drainage is adequate for Acorn Squash.

Organic Matter

Organic matter is moderate (2.3%). Annual compost additions will help Acorn Squash.

How to Plant Acorn Squash

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

Succession Planting Acorn Squash

2
successive plantings in your 157-day season

Sow every 9.1 weeks. Last sowing by Jun 28 to harvest before frost.

Plant Water Budget

Plant needs
1.1″/week
Rainfall provides
0.6″/week
You supply
1.0″/week
Watering frequency 2-3 times/week
Season total 1,348 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Acorn Squash

Acorn 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 Acorn Squash Needs Rainfall You Supplement Action
Jan 1.7" 0" ❄️ Dormant
Feb 1.3" 0" ❄️ Dormant
Mar 2.1" 0" ❄️ Dormant
Apr 2.2" 0" ❄️ Dormant
May 4.8" 2.5" 2.3" 💧 Light watering
Jun 4.8" 1.9" 2.9" 🚿 Regular watering
Jul 4.8" 2.3" 2.5" 🚿 Regular watering
Aug 4.8" 2.5" 2.3" 💧 Light watering
Sep 4.8" 2" 2.8" 🚿 Regular watering
Oct 4.8" 1.9" 2.9" 🚿 Regular watering
Nov 1.7" 0" ❄️ Dormant
Dec 1.3" 0" ❄️ Dormant

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

Acorn 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.

Acorn Squash needs ~1,170 GDD — county provides 2,041 GDD Excellent fit

Acorn Squash Planting Timeline — Larimer County, CO

Acorn Squash Planting Calendar

Activity When Date Range
Start Indoors March 28 Mar 28 – Apr 11
Transplant Outdoors May 16 May 16 – May 30
Direct Sow May 9 May 9 – May 30
Harvest August 8 Aug 8 – Sep 12

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

Month-by-Month Timeline

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

80–100 days

🧪 Soil pH

Needs 5.5–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 5b

📆 Growing Season

157 days in Larimer County

Growing Tips for Acorn Squash in Larimer County

Direct sow Acorn Squash outdoors after May 02 in Larimer County when soil has warmed and frost danger has passed.

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

Larimer County receives only 23" of rain annually. Acorn Squash needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

General growing tips

Direct sow after last frost. Harvest when the ground spot turns orange and the skin is hard. Acorn squash has a shorter storage life than butternut, lasting about 2 months.

Companion Planting

Good Companions

Avoid Planting Near

  • Potatoes

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Acorn Squash in Larimer County, CO?

Larimer County is in Zone 5b with an average last frost of May 2. Plan your Acorn Squash planting based on this frost date — see the calendar above for exact timing.

What planting zone is Larimer County, CO?

Larimer County, Colorado is in USDA Hardiness Zone 5b. The average last spring frost is May 2 and first fall frost is October 6.

🌱

Your Larimer County Garden Planner — Free

A 24-page printable planner built for Larimer County (Zone 5b). 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 Larimer County, CO. 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.