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When to Plant Hubbard Squash in Muscatine County, IA

Muscatine County, Iowa Zone 5b May

Your May game plan for Muscatine County, Iowa

May is a pivotal month for Muscatine County, Iowa gardens. Focus on these tasks first and you'll set up the rest of the season for success.

Avg. last frost April 17
Avg. first frost October 16
Soil temp (4") 58°F
Watering Low
Pest pressure Low
Daylight 14.3 hrs
  1. Set out hubbard squash seedlings

    Water the tray well an hour before you transplant. Roots slide out cleanly and settle in faster.

  2. Fire up the seed-starting tray: hubbard squash

    You're about 23 weeks out from your last frost — the perfect window to get these germinating indoors.

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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.

Muscatine County, Iowa is in USDA Zone 5b. The average last spring frost is April 17 and the first fall frost is October 16, giving you a growing season of approximately 182 days.

At an elevation of 898 feet, Muscatine County receives approximately 34.8 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83°F, so choose short-season varieties of Hubbard Squash to ensure they mature before fall.

Muscatine County, IA (Zone 5b) Moderate season
182 days
Last Spring Frost April 17
182 growing days
First Fall Frost October 16
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Muscatine County Soil Profile

Soil Type

Silt Loam

Soil pH

5.9-7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (26 days to spare)
Start indoors: Mar 8 Transplant: Apr 26 🍅 Harvest: Aug 9 – Sep 13
Recommended (50%) ✓ Fits season (28 days to spare)
Start indoors: Mar 13 Transplant: May 1 🍅 Harvest: Aug 14 – Sep 18
Safe Start (90%) ✓ Fits season (24 days to spare)
Start indoors: Apr 3 Transplant: May 22 🍅 Harvest: Sep 4 – Oct 9

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 Muscatine County

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

Soil pH

Your soil pH (5.9–7.0) overlaps with Hubbard Squash's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is excellent (4.5%) — 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
0.8″/week
You supply
0.2″/week
Watering frequency Only during dry spells
Season total 319 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 1.4" 0" ❄️ Dormant
Feb 1.4" 0" ❄️ Dormant
Mar 2.1" 0" ❄️ Dormant
Apr 4.3" 3.2" 1.1" 💧 Light watering
May 4.3" 3.8" 0.5" 💧 Light watering
Jun 4.3" 4.2" 0.1" 💧 Light watering
Jul 4.3" 4.1" 0.2" 💧 Light watering
Aug 4.3" 4.1" 0.2" 💧 Light watering
Sep 4.3" 3" 1.3" 💧 Light watering
Oct 4.3" 3" 1.3" 💧 Light watering
Nov 2.4" 0" ❄️ Dormant
Dec 2.1" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Muscatine 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 2,229 GDD Excellent fit

Hubbard Squash Planting Timeline — Muscatine County, IA

Hubbard Squash Planting Calendar

Activity When Date Range
Start Indoors March 13 Mar 13 – Mar 27
Transplant Outdoors May 1 May 1 – May 15
Direct Sow April 24 Apr 24 – May 15
Harvest August 14 Aug 14 – Sep 18

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

Month-by-Month Timeline

MonthActivities
January
February
March Start Indoors
April Direct Sow
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"/week · Only during dry spells

📅 Days to Maturity

100–120 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 5b

📆 Growing Season

182 days in Muscatine County

Growing Tips for Hubbard Squash in Muscatine County

Direct sow Hubbard Squash outdoors after April 17 in Muscatine 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 Muscatine County, IA?

Muscatine County is in Zone 5b with an average last frost of April 17. Plan your Hubbard Squash planting based on this frost date — see the calendar above for exact timing.

What planting zone is Muscatine County, IA?

Muscatine County, Iowa is in USDA Hardiness Zone 5b. The average last spring frost is April 17 and first fall frost is October 16.

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Your Muscatine County Garden Planner — Free

A 24-page printable planner built for Muscatine 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 Muscatine County, IA. 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.