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When to plant Kabocha in Clay County, MN

Clay County sits in cold Zone 4a. Plant Kabocha May 25–June 15 for the single annual harvest; the September 30 first frost closes the window.

When to Plant Kabocha in Clay County, MN

Clay County, Minnesota Zone 4a June

June to-do list for Clay County, Minnesota

Welcome to June in Zone 4a. These are the moves that will have the biggest impact on your growing season.

Avg. last frost May 11
Avg. first frost September 30
Soil temp (4") 59°F
Watering Low
Pest pressure Moderate
Daylight 15.7 hrs
  1. Harden off and plant kabocha

    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. Fire up the seed-starting tray: kabocha

    Your window is short. These crops want several weeks of indoor growth before they go outside.

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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.

Clay County, Minnesota is in USDA Zone 4a. The average last spring frost is May 11 and the first fall frost is September 30, giving you a growing season of approximately 142 days.

At an elevation of 1,220 feet, Clay County receives approximately 35.3 inches of rainfall annually with predominantly silt loam soil. Summer highs average 80°F, so choose short-season varieties of Kabocha to ensure they mature before fall.

Clay County, MN (Zone 4a) Short season
142 days
Last Spring Frost May 11
142 growing days
First Fall Frost September 30

Clay County Soil Profile

Soil Type

Silt Loam

Soil pH

5.9-6.9

Drainage

Well Drained

Kabocha Planting Risk Windows

Early Start (70% safe) ✓ Fits season (5 days to spare)
Start indoors: Mar 21 Transplant: May 23 🍅 Harvest: Aug 22 – Sep 19
Recommended (50%) ✓ Fits season (2 days to spare)
Start indoors: Mar 30 Transplant: Jun 1 🍅 Harvest: Aug 31 – Sep 28
Safe Start (90%) ✓ Fits season (4 days to spare)
Start indoors: Apr 11 Transplant: Jun 13 🍅 Harvest: Sep 12 – Oct 10

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 Clay County

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

Soil pH

Your soil pH (5.9–6.9) overlaps with Kabocha's range (6.0–7.5), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is excellent (4.6%) — Kabocha will thrive.

How to Plant Kabocha

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

Kabocha Water Budget

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

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

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 1.4" 0" ❄️ Dormant
Feb 1.5" 0" ❄️ Dormant
Mar 2.8" 0" ❄️ Dormant
Apr 3.9" 0" ❄️ Dormant
May 4.3" 3.8" 0.5" 💧 Light watering
Jun 4.3" 3.8" 0.5" 💧 Light watering
Jul 4.3" 4.3" 0" ✅ Rainfall sufficient
Aug 4.3" 4.2" 0.1" 💧 Light watering
Sep 4.3" 2.8" 1.5" 💧 Light watering
Oct 2.6" 0" ❄️ Dormant
Nov 2.2" 0" ❄️ Dormant
Dec 2.2" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Clay 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 ~925 GDD — county provides 1,420 GDD Excellent fit

Kabocha Planting Timeline — Clay County, MN

Kabocha Planting Calendar

Activity When Date Range
Start Indoors March 30 Mar 30 – Apr 13
Transplant Outdoors June 1 Jun 1 – Jun 15
Direct Sow May 25 May 25 – Jun 15
Harvest August 31 Aug 31 – Sep 28

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Natural rainfall sufficient

📅 Days to Maturity

85–100 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 4a

📆 Growing Season

142 days in Clay County

Growing Tips for Kabocha in Clay County

Direct sow Kabocha outdoors after May 11 in Clay 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 Clay County, MN?

Clay County is in Zone 4a with an average last frost of May 11. Plan your Kabocha planting based on this frost date — see the calendar above for exact timing.

What planting zone is Clay County, MN?

Clay County, Minnesota is in USDA Hardiness Zone 4a. The average last spring frost is May 11 and first fall frost is September 30.

When should I plant Kabocha in Clay County, MN?

In Clay County, MN, plant Kabocha after the last frost (around May 11) and before the first frost (around September 30). Best results when soil holds above 50°F.

What growing zone is Clay County, MN for Kabocha?

Clay County sits in USDA Zone 4a. Kabocha grows reliably in zones 3a through 11b, so it's a good fit here.

Can Kabocha grow in Clay County's climate?

Yes — Kabocha grows well in Clay County's temperate climate. Clay County averages a 142-day frost-free season, with last frost around May 11 and first frost around September 30.

🌱

Your Clay County Garden Planner — Free

A 22-page printable planner built for Clay County (Zone 4a). 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 Clay County, MN. Local conditions may vary. Last updated: June 2026.

Sources & credits

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