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When to Plant Hubbard Squash in Clear Creek County, CO

Clear Creek County, Colorado Zone 5a May

May in Clear Creek County, Colorado — your action list

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

Avg. last frost May 14
Avg. first frost September 26
Soil temp (4") 35°F
Watering High
Pest pressure Low
Daylight 14.2 hrs
  1. Set out hubbard squash seedlings

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

  2. Direct-sow hubbard squash

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

Get ahead of June
  • Starting indoors: hubbard squash

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Hubbard squash is a large, bumpy-skinned winter squash with dense, sweet, dry flesh ideal for baking and pies. The hard shell allows storage for 6 months or more.

Clear Creek County, Colorado is in USDA Zone 5a. The average last spring frost is May 14 and the first fall frost is September 26, giving you a growing season of approximately 135 days.

At an elevation of 6,538 feet, Clear Creek County receives approximately 24.6 inches of rainfall annually with predominantly loam soil. Summer highs average 83°F, so choose short-season varieties of Hubbard Squash to ensure they mature before fall.

Clear Creek County, CO (Zone 5a) Short season
135 days
Last Spring Frost May 14
135 growing days
First Fall Frost September 26

Clear Creek County Soil Profile

Soil Type

Loam

Soil pH

6.8-8.1

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Mar 29 Transplant: May 17 🍅 Harvest: Aug 30 – Oct 4
Recommended (50%) ✗ May not fit
Start indoors: Apr 9 Transplant: May 28 🍅 Harvest: Sep 10 – Oct 15
Safe Start (90%) ✗ May not fit
Start indoors: May 6 Transplant: Jun 24 🍅 Harvest: Oct 7 – Nov 11

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 Clear Creek County

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

Soil pH

Your soil pH (6.8–8.1) is more alkaline than Hubbard Squash prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

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

How to Plant Hubbard Squash

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

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.8″/week
You supply
0.3″/week
Watering frequency Only during dry spells
Season total 338 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Hubbard Squash

Hubbard Squash needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Hubbard Squash Needs Rainfall You Supplement Action
Jan 1.9" 0" ❄️ Dormant
Feb 1.5" 0" ❄️ Dormant
Mar 1.9" 0" ❄️ Dormant
Apr 2.7" 0" ❄️ Dormant
May 4.3" 2.7" 1.6" 💧 Light watering
Jun 4.3" 1.7" 2.6" 🚿 Regular watering
Jul 4.3" 2.4" 1.9" 💧 Light watering
Aug 4.3" 2.4" 1.9" 💧 Light watering
Sep 4.3" 2.1" 2.2" 🚿 Regular watering
Oct 2.3" 0" ❄️ Dormant
Nov 1.9" 0" ❄️ Dormant
Dec 1.2" 0" ❄️ Dormant

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

Hubbard 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.

Hubbard Squash needs ~1,348 GDD — county provides 1,653 GDD Good fit

Hubbard Squash Planting Timeline — Clear Creek County, CO

Hubbard Squash Planting Calendar

Activity When Date Range
Start Indoors April 9 Apr 9 – Apr 23
Transplant Outdoors May 28 May 28 – Jun 11
Direct Sow May 21 May 21 – Jun 11
Harvest September 10 Sep 10 – Oct 15

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
September Harvest
October Harvest
November
December

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Only during dry spells

📅 Days to Maturity

100–120 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 5a

📆 Growing Season

135 days in Clear Creek County

Growing Tips for Hubbard Squash in Clear Creek County

Direct sow Hubbard Squash outdoors after May 14 in Clear Creek County when soil has warmed and frost danger has passed.

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

Clear Creek County receives only 25" of rain annually. Hubbard Squash needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

General growing tips

Start seeds indoors in short-season areas. Requires ample space and rich soil. Harvest when the skin is very hard and the color is deep. Cure in the sun before storing.

Companion Planting

Good Companions

Avoid Planting Near

  • Potatoes

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Hubbard Squash in Clear Creek County, CO?

Clear Creek County is in Zone 5a with an average last frost of May 14. Plan your Hubbard Squash planting based on this frost date — see the calendar above for exact timing.

What planting zone is Clear Creek County, CO?

Clear Creek County, Colorado is in USDA Hardiness Zone 5a. The average last spring frost is May 14 and first fall frost is September 26.

🌱

Your Clear Creek County Garden Planner — Free

A 24-page printable planner built for Clear Creek 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 Clear Creek 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.