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When to Plant Hubbard Squash in Iosco County, MI

Iosco County, Michigan Zone 5b May

What to do in May

We've pulled the most time-sensitive tasks for Iosco County, Michigan this May and put them front and centre. Tackle them in order.

Avg. last frost May 14
Avg. first frost October 3
Soil temp (4") 60°F
Watering Low
Pest pressure Low
Daylight 14.6 hrs
  1. Move hubbard squash from tray to bed

    Plant tomatoes deep — bury the stem up to the first true leaves to grow extra roots. Everything else goes in at the same depth it grew in the tray.

  2. Direct-sow hubbard squash

    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: 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.

Iosco County, Michigan is in USDA Zone 5b. The average last spring frost is May 14 and the first fall frost is October 3, giving you a growing season of approximately 142 days.

At an elevation of 696 feet, Iosco County receives approximately 37.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 88°F, providing good warmth for Hubbard Squash during the growing season.

Iosco County, MI (Zone 5b) Short season
142 days
Last Spring Frost May 14
142 growing days
First Fall Frost October 3

Iosco County Soil Profile

Soil Type

Silt Loam

Soil pH

6.2-6.9

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Apr 3 Transplant: May 22 🍅 Harvest: Sep 4 – Oct 9
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: Apr 23 Transplant: Jun 11 🍅 Harvest: Sep 24 – Oct 29

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 Iosco County

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

Soil pH

Your soil pH (6.2–6.9) is within Hubbard Squash's preferred range (6.0–7.0).

Soil Texture

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

Organic Matter

Organic matter is excellent (4.4%) — 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

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 1.7" 0" ❄️ Dormant
Feb 1.6" 0" ❄️ Dormant
Mar 2.9" 0" ❄️ Dormant
Apr 3.8" 0" ❄️ Dormant
May 4.3" 4.7" 0" ✅ Rainfall sufficient
Jun 4.3" 4.7" 0" ✅ Rainfall sufficient
Jul 4.3" 3.6" 0.7" 💧 Light watering
Aug 4.3" 4" 0.3" 💧 Light watering
Sep 4.3" 2.9" 1.4" 💧 Light watering
Oct 4.3" 2.7" 1.6" 💧 Light watering
Nov 2.8" 0" ❄️ Dormant
Dec 2" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Iosco 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 ~1,760 GDD — county provides 2,272 GDD Good fit

Hubbard Squash Planting Timeline — Iosco County, MI

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 · Natural rainfall sufficient

📅 Days to Maturity

100–120 days

🧪 Soil pH

Needs 6–7 · Your soil: ideal

🗺️ USDA Zone

Zone 5b

📆 Growing Season

142 days in Iosco County

Growing Tips for Hubbard Squash in Iosco County

Direct sow Hubbard Squash outdoors after May 14 in Iosco 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 Iosco County, MI?

Iosco County is in Zone 5b 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 Iosco County, MI?

Iosco County, Michigan is in USDA Hardiness Zone 5b. The average last spring frost is May 14 and first fall frost is October 3.

🌱

Your Iosco County Garden Planner — Free

A 24-page printable planner built for Iosco 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 Iosco County, MI. 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.