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When to Plant Hubbard Squash in Roscommon County, MI

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.

Roscommon County, Michigan is in USDA Zone 5a. The average last spring frost is May 15 and the first fall frost is October 2, giving you a growing season of approximately 140 days.

At an elevation of 1,298 feet, Roscommon County receives approximately 36 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83ยฐF, so choose short-season varieties of Hubbard Squash to ensure they mature before fall.

Roscommon County, MI (Zone 5a) Short season
140 days
Last Spring Frost May 15
140 growing days
First Fall Frost October 2

Roscommon County Soil Profile

Soil Type

Silt Loam

Soil pH

6-6.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Apr 5 Transplant: May 24 🍅 Harvest: Sep 6 – Oct 11
Recommended (50%) ✗ May not fit
Start indoors: Apr 10 Transplant: May 29 🍅 Harvest: Sep 11 – Oct 16
Safe Start (90%) ✗ May not fit
Start indoors: Apr 26 Transplant: Jun 14 🍅 Harvest: Sep 27 – Nov 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 Roscommon County

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

Soil pH

Your soil pH (6.0โ€“6.8) is within Hubbard Squash's preferred range (6.0โ€“7.0).

Soil Texture

The silt loam soil in Roscommon County is excellent for Hubbard Squash โ€” good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is excellent (4.2%) โ€” Hubbard Squash will thrive.

How to Plant Hubbard Squash

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

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
1.1″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Drought risk

Water stress score is 6/10 โ€” 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 โ€” 1.5" 0" โ„๏ธ Dormant
Feb โ€” 1.6" 0" โ„๏ธ Dormant
Mar โ€” 2.2" 0" โ„๏ธ Dormant
Apr โ€” 3.5" 0" โ„๏ธ Dormant
May 4.3" 4.3" 0" โœ… Rainfall sufficient
Jun 4.3" 4.5" 0" โœ… Rainfall sufficient
Jul 4.3" 4.4" 0" โœ… Rainfall sufficient
Aug 4.3" 3.9" 0.4" ๐Ÿ’ง Light watering
Sep 4.3" 3.2" 1.1" ๐Ÿ’ง Light watering
Oct 4.3" 2.5" 1.8" ๐Ÿ’ง Light watering
Nov โ€” 2.3" 0" โ„๏ธ Dormant
Dec โ€” 2.1" 0" โ„๏ธ Dormant

Water needs are for active growing months only (Mayโ€“Oct in Roscommon County). Supplement amounts are based on average rainfall โ€” 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" โ€” every day above 50ยฐF 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 1,715 GDD Good fit

Hubbard Squash Planting Timeline โ€” Roscommon County, MI

Hubbard Squash Planting Calendar

Activity When Date Range
Start Indoors April 10 Apr 10 โ€“ Apr 24
Transplant Outdoors May 29 May 29 โ€“ Jun 12
Direct Sow May 22 May 22 โ€“ Jun 12
Harvest September 11 Sep 11 โ€“ Oct 16

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 Transplant Outdoors Direct Sow
June Transplant Outdoors Direct Sow
July โ€”
August โ€”
September Harvest
October Harvest
November โ€”
December โ€”

Growing Conditions

โ˜€๏ธ Sun

Full Sun (6-8+ hours)

๐Ÿ’ง Water

1"/week ยท Natural rainfall sufficient

๐Ÿ“… Days to Maturity

100โ€“120 days

๐Ÿงช Soil pH

Needs 6โ€“7 ยท Your soil: ideal

๐Ÿ—บ๏ธ USDA Zone

Zone 5a

๐Ÿ“† Growing Season

140 days in Roscommon County

Growing Tips for Hubbard Squash in Roscommon County

Direct sow Hubbard Squash outdoors after May 15 in Roscommon 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.

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 Roscommon County, MI?

Roscommon County is in Zone 5a with an average last frost of May 15. Plan your Hubbard Squash planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Roscommon County, MI?

Roscommon County, Michigan is in USDA Hardiness Zone 5a. The average last spring frost is May 15 and first fall frost is October 2.

๐ŸŒฑ

Plan Your Garden with Confidence

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

Get Your Free Garden Planner →

Free download. Plan your entire garden season in minutes.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Roscommon County, MI. Local conditions may vary. Last updated: April 2026.