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When to Plant Spaghetti Squash in St. Louis County, MN

St. Louis County, Minnesota Zone 3b May

May to-do list for St. Louis County, Minnesota

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

Avg. last frost June 2
Avg. first frost September 10
Soil temp (4") 49°F
Watering Low
Pest pressure Low
Daylight 14.9 hrs
Looking ahead to June
  • Transplants going out: spaghetti squash
  • Direct-sowing: spaghetti squash

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Spaghetti squash is a winter squash whose cooked flesh separates into pasta-like strands. It is a popular low-carb alternative to pasta.

St. Louis County, Minnesota is in USDA Zone 3b. The average last spring frost is June 2 and the first fall frost is September 10, giving you a growing season of approximately 100 days.

At an elevation of 531 feet, St. Louis County receives approximately 36.3 inches of rainfall annually with predominantly silt loam soil. Summer highs average 78°F, so choose short-season varieties of Spaghetti Squash to ensure they mature before fall.

St. Louis County, MN (Zone 3b) Short season
100 days
Last Spring Frost June 2
100 growing days
First Fall Frost September 10

St. Louis County Soil Profile

Soil Type

Silt Loam

Soil pH

6-7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Apr 16 Transplant: Jun 18 🍅 Harvest: Sep 17 – Oct 15
Recommended (50%) ✗ May not fit
Start indoors: Apr 21 Transplant: Jun 23 🍅 Harvest: Sep 22 – Oct 20
Safe Start (90%) ✗ May not fit
Start indoors: May 5 Transplant: Jul 7 🍅 Harvest: Oct 6 – Nov 3

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 St. Louis County

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

Soil pH

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

Soil Texture

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

Drainage

Drainage is adequate for Spaghetti Squash.

Organic Matter

Organic matter is excellent (4.0%) — Spaghetti Squash will thrive.

How to Plant Spaghetti Squash

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

Plant Water Budget

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

Monthly Watering Guide for Spaghetti Squash

Spaghetti 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 Spaghetti Squash Needs Rainfall You Supplement Action
Jan 1.6" 0" ❄️ Dormant
Feb 1.7" 0" ❄️ Dormant
Mar 2.7" 0" ❄️ Dormant
Apr 3.2" 0" ❄️ Dormant
May 3.9" 0" ❄️ Dormant
Jun 4.3" 5.1" 0" ✅ Rainfall sufficient
Jul 4.3" 4.4" 0" ✅ Rainfall sufficient
Aug 4.3" 3.7" 0.6" 💧 Light watering
Sep 4.3" 3.1" 1.2" 💧 Light watering
Oct 2.8" 0" ❄️ Dormant
Nov 2.3" 0" ❄️ Dormant
Dec 1.8" 0" ❄️ Dormant

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

Spaghetti 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.

Spaghetti Squash needs ~786 GDD — county provides 850 GDD Good fit

Spaghetti Squash Planting Timeline — St. Louis County, MN

Spaghetti Squash Planting Calendar

Activity When Date Range
Start Indoors April 21 Apr 21 – May 5
Transplant Outdoors June 23 Jun 23 – Jul 7
Direct Sow June 16 Jun 16 – Jul 7
Harvest September 22 Sep 22 – Oct 20

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

Month-by-Month Timeline

MonthActivities
January
February
March
April Start Indoors
May Start Indoors
June Transplant Outdoors Direct Sow
July Transplant Outdoors Direct Sow
August
September Harvest
October Harvest
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 · Your soil: ideal

🗺️ USDA Zone

Zone 3b

📆 Growing Season

100 days in St. Louis County

Growing Tips for Spaghetti Squash in St. Louis County

Direct sow Spaghetti Squash outdoors after June 02 in St. Louis County when soil has warmed and frost danger has passed.

Your 100.0-day growing season in St. Louis County is tight for Spaghetti Squash (85.0-100.0 days to maturity). Start indoors and choose early-maturing varieties.

Common pests for Spaghetti 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

Direct sow on mounds after last frost. Harvest when skin turns golden yellow and is hard. Store in a cool, dry place for 2-3 months. Bake or microwave halves until tender.

Companion Planting

Good Companions

Avoid Planting Near

  • Potatoes

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Spaghetti Squash in St. Louis County, MN?

St. Louis County is in Zone 3b with an average last frost of June 2. Plan your Spaghetti Squash planting based on this frost date — see the calendar above for exact timing.

What planting zone is St. Louis County, MN?

St. Louis County, Minnesota is in USDA Hardiness Zone 3b. The average last spring frost is June 2 and first fall frost is September 10.

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Your St. Louis County Garden Planner — Free

A 24-page printable planner built for St. Louis County (Zone 3b). 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 St. Louis County, MN. 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.