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When to Plant Kabocha in Shiawassee County, MI

Shiawassee County, Michigan Zone 6a May

Top priorities for Shiawassee County, Michigan gardeners in May

Your garden in Shiawassee County, Michigan is working on a schedule, even when you're not. Here's where you should be this May.

Avg. last frost April 29
Avg. first frost October 14
Soil temp (4") 58°F
Watering Moderate
Pest pressure Low
Daylight 14.5 hrs
  1. Transplant kabocha outside

    Harden off for 7 days — a little more sun each day — before planting. That's the difference between a seedling that thrives and one that stalls.

  2. Put kabocha seeds straight in the ground

    These tolerate cool soil, so you're not gambling by sowing now.

To set up a strong June, finish these tasks
  • Starting indoors: kabocha

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Kabocha is a Japanese winter squash with an exceptionally sweet, dense, chestnut-like flesh and dark green skin. It is a favorite in Asian cuisine for its rich, dry texture.

Shiawassee County, Michigan is in USDA Zone 6a. The average last spring frost is April 29 and the first fall frost is October 14, giving you a growing season of approximately 168 days.

At an elevation of 803 feet, Shiawassee County receives approximately 30.8 inches of rainfall annually with predominantly silt loam soil. Summer highs average 87°F, providing good warmth for Kabocha during the growing season.

Shiawassee County, MI (Zone 6a) Moderate season
168 days
Last Spring Frost April 29
168 growing days
First Fall Frost October 14
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Shiawassee County Soil Profile

Soil Type

Silt Loam

Soil pH

5.7-6.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (30 days to spare)
Start indoors: Mar 22 Transplant: May 10 🍅 Harvest: Aug 9 – Sep 6
Recommended (50%) ✓ Fits season (35 days to spare)
Start indoors: Mar 25 Transplant: May 13 🍅 Harvest: Aug 12 – Sep 9
Safe Start (90%) ✓ Fits season (30 days to spare)
Start indoors: Apr 10 Transplant: May 29 🍅 Harvest: Aug 28 – Sep 25

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 Shiawassee County

How your county's soil matches Kabocha's growing requirements.

Soil pH

Your soil pH (5.7–6.8) overlaps with Kabocha's range (6.0–7.5), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is excellent (4.7%) — Kabocha will thrive.

How to Plant Kabocha

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 344 gal / 100 sq ft

Monthly Watering Guide for Kabocha

Kabocha needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Kabocha Needs Rainfall You Supplement Action
Jan 1.1" 0" ❄️ Dormant
Feb 1.5" 0" ❄️ Dormant
Mar 2.3" 0" ❄️ Dormant
Apr 4.3" 2.8" 1.5" 💧 Light watering
May 4.3" 3.5" 0.8" 💧 Light watering
Jun 4.3" 4.4" 0" ✅ Rainfall sufficient
Jul 4.3" 2.9" 1.4" 💧 Light watering
Aug 4.3" 3.3" 1" 💧 Light watering
Sep 4.3" 2.9" 1.4" 💧 Light watering
Oct 4.3" 2.3" 2" 💧 Light watering
Nov 2" 0" ❄️ Dormant
Dec 1.9" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Shiawassee County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Kabocha 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.

Kabocha needs ~1,411 GDD — county provides 2,562 GDD Excellent fit

Kabocha Planting Timeline — Shiawassee County, MI

Kabocha Planting Calendar

Activity When Date Range
Start Indoors March 25 Mar 25 – Apr 8
Transplant Outdoors May 13 May 13 – May 27
Direct Sow May 6 May 6 – May 27
Harvest August 12 Aug 12 – Sep 9

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
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Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Only during dry spells

📅 Days to Maturity

85–100 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 6a

📆 Growing Season

168 days in Shiawassee County

Growing Tips for Kabocha in Shiawassee County

Direct sow Kabocha outdoors after April 29 in Shiawassee County when soil has warmed and frost danger has passed.

Common pests for Kabocha in this region include squash vine borer and cucumber beetles. Use row covers early in the season and inspect plants weekly.

General growing tips

Direct sow after frost or start indoors. Harvest when the skin is hard and dull. The stem should be dry and corky. Stores well for 3-4 months in a cool, dry place.

Companion Planting

Good Companions

Avoid Planting Near

  • Potatoes

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Kabocha in Shiawassee County, MI?

Shiawassee County is in Zone 6a with an average last frost of April 29. Plan your Kabocha planting based on this frost date — see the calendar above for exact timing.

What planting zone is Shiawassee County, MI?

Shiawassee County, Michigan is in USDA Hardiness Zone 6a. The average last spring frost is April 29 and first fall frost is October 14.

🌱

Your Shiawassee County Garden Planner — Free

A 24-page printable planner built for Shiawassee County (Zone 6a). 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 Shiawassee 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.