Blog

When to Plant Hubbard Squash in Rock County, WI

Rock County, Wisconsin Zone 5b May

This month in Rock County, Wisconsin

If you only do a handful of things in the garden this May, make it these. They're sequenced around your zone's frost timing.

Avg. last frost April 26
Avg. first frost October 13
Soil temp (4") 57°F
Watering Moderate
Pest pressure Low
Daylight 14.4 hrs
  1. Plant out hubbard squash

    Pick a cloudy afternoon or evening to plant. Less transplant shock, and your seedlings will barely blink.

  2. Scatter hubbard squash into prepared beds

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

  3. Start hubbard squash under lights

    You're about 22 weeks out from your last frost — the perfect window to get these germinating indoors.

Instant PDF download. No spam, unsubscribe any time.

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.

Rock County, Wisconsin is in USDA Zone 5b. The average last spring frost is April 26 and the first fall frost is October 13, giving you a growing season of approximately 170 days.

At an elevation of 710 feet, Rock County receives approximately 30.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 86°F, providing good warmth for Hubbard Squash during the growing season.

Rock County, WI (Zone 5b) Moderate season
170 days
Last Spring Frost April 26
170 growing days
First Fall Frost October 13
Share this guide:

Rock County Soil Profile

Soil Type

Silt Loam

Soil pH

6.2-7.1

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (16 days to spare)
Start indoors: Mar 17 Transplant: May 5 🍅 Harvest: Aug 18 – Sep 22
Recommended (50%) ✓ Fits season (16 days to spare)
Start indoors: Mar 22 Transplant: May 10 🍅 Harvest: Aug 23 – Sep 27
Safe Start (90%) ✓ Fits season (15 days to spare)
Start indoors: Apr 6 Transplant: May 25 🍅 Harvest: Sep 7 – Oct 12

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 Rock County

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

Soil pH

Your soil pH (6.2–7.1) overlaps with Hubbard Squash's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is excellent (5.1%) — 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
0.3″/week
Watering frequency Only during dry spells
Season total 452 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — 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 1.3" 0" ❄️ Dormant
Feb 1.4" 0" ❄️ Dormant
Mar 2.1" 0" ❄️ Dormant
Apr 4.3" 3.3" 1" 💧 Light watering
May 4.3" 3.1" 1.2" 💧 Light watering
Jun 4.3" 3.8" 0.5" 💧 Light watering
Jul 4.3" 3.2" 1.1" 💧 Light watering
Aug 4.3" 3" 1.3" 💧 Light watering
Sep 4.3" 2.8" 1.5" 💧 Light watering
Oct 4.3" 2.6" 1.7" 💧 Light watering
Nov 2.4" 0" ❄️ Dormant
Dec 1.5" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Rock 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 ~1,595 GDD — county provides 2,465 GDD Excellent fit

Hubbard Squash Planting Timeline — Rock County, WI

Hubbard Squash Planting Calendar

Activity When Date Range
Start Indoors March 22 Mar 22 – Apr 5
Transplant Outdoors May 10 May 10 – May 24
Direct Sow May 3 May 3 – May 24
Harvest August 23 Aug 23 – Sep 27

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

Month-by-Month Timeline

MonthActivities
January
February
March Start Indoors
April Start Indoors
May Transplant Outdoors Direct Sow
June
July
August Harvest
September Harvest
October
November
December
Share this guide:

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

170 days in Rock County

Growing Tips for Hubbard Squash in Rock County

Direct sow Hubbard Squash outdoors after April 26 in Rock 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 Rock County, WI?

Rock County is in Zone 5b with an average last frost of April 26. Plan your Hubbard Squash planting based on this frost date — see the calendar above for exact timing.

What planting zone is Rock County, WI?

Rock County, Wisconsin is in USDA Hardiness Zone 5b. The average last spring frost is April 26 and first fall frost is October 13.

🌱

Your Rock County Garden Planner — Free

A 24-page printable planner built for Rock 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.

Instant PDF download. No spam, unsubscribe any time.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Rock County, WI. 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.