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When to Plant Hubbard Squash in Rio Blanco County, CO

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.

Rio Blanco County, Colorado is in USDA Zone 5a. The average last spring frost is June 2 and the first fall frost is September 17, giving you a growing season of approximately 107 days.

At an elevation of 6,974 feet, Rio Blanco County receives approximately 19 inches of rainfall annually with predominantly loam soil. Summer highs average 86ยฐF, providing good warmth for Hubbard Squash during the growing season. With low rainfall, drip irrigation is essential for growing Hubbard Squash successfully. Mulch heavily to conserve soil moisture.

Rio Blanco County, CO (Zone 5a) Short season
107 days
Last Spring Frost June 2
107 growing days
First Fall Frost September 17

Rio Blanco County Soil Profile

Soil Type

Loam

Soil pH

6.4-7.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Apr 14 Transplant: Jun 2 🍅 Harvest: Sep 15 – Oct 20
Recommended (50%) ✗ May not fit
Start indoors: Apr 28 Transplant: Jun 16 🍅 Harvest: Sep 29 – Nov 3
Safe Start (90%) ✗ May not fit
Start indoors: May 16 Transplant: Jul 4 🍅 Harvest: Oct 17 – Nov 21

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.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.8″/week
You supply
0.3″/week
Watering frequency 1-2 times/week
Season total 290 gal / 100 sq ft
Drought risk

Water stress score is 8/10 โ€” consider drought-tolerant varieties and mulching

Hubbard Squash needs ~1,595 GDD — county provides 1,551 GDD Tight fit

Hubbard Squash Planting Timeline โ€” Rio Blanco County, CO

Hubbard Squash Planting Calendar

Activity When Date Range
Start Indoors April 28 Apr 28 โ€“ May 12
Transplant Outdoors June 16 Jun 16 โ€“ Jun 30
Direct Sow June 9 Jun 9 โ€“ Jun 30
Harvest September 29 Sep 29 โ€“ Nov 3

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

Month-by-Month Timeline

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

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Moderate โ€” regular watering

Days to Maturity

100โ€“120 days

Soil pH

6 โ€“ 7

USDA Zone

Zone 5a

Growing Season

107 days

Growing Tips for Rio Blanco County

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

Level Up Your Garden

Frequently Asked Questions

When should I plant Hubbard Squash in Rio Blanco County, CO?

Rio Blanco County is in Zone 5a with an average last frost of June 2. Plan your Hubbard Squash planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Rio Blanco County, CO?

Rio Blanco County, Colorado is in USDA Hardiness Zone 5a. The average last spring frost is June 2 and first fall frost is September 17.

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Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Rio Blanco County gardeners in Zone 5a organize planting dates, track what's growing, and never miss a planting window.

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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 Rio Blanco County, CO. Local conditions may vary. Last updated: April 2026.