Blog

When to Plant Zucchini in Carlton County, MN

Carlton County, Minnesota Zone 4a May

Your May gardening checklist

We've pulled the most time-sensitive tasks for Carlton County, Minnesota this May and put them front and centre. Tackle them in order.

Avg. last frost May 12
Avg. first frost October 2
Soil temp (4") 49°F
Watering Moderate
Pest pressure Low
Daylight 14.8 hrs
  1. Seed zucchini outdoors

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

A few tasks this May that'll pay off in June
  • Transplants going out: zucchini
  • Starting indoors: zucchini

Instant PDF download. No spam, unsubscribe any time.

Zucchini is an incredibly prolific summer squash that can produce an abundance of fruit from just a few plants. It is versatile in the kitchen from grilling to baking.

Carlton County, Minnesota is in USDA Zone 4a. The average last spring frost is May 12 and the first fall frost is October 2, giving you a growing season of approximately 143 days.

At an elevation of 516 feet, Carlton County receives approximately 32.8 inches of rainfall annually with predominantly silt loam soil. Summer highs average 82°F, so choose short-season varieties of Zucchini to ensure they mature before fall.

Carlton County, MN (Zone 4a) Short season
143 days
Last Spring Frost May 12
143 growing days
First Fall Frost October 2
Share this guide:

Carlton 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 24 Transplant: May 26 🍅 Harvest: Jul 14 – Sep 8
Recommended (50%) ✓ Fits season (17 days to spare)
Start indoors: Mar 31 Transplant: Jun 2 🍅 Harvest: Jul 21 – Sep 15
Safe Start (90%) ✓ Fits season (12 days to spare)
Start indoors: Apr 19 Transplant: Jun 21 🍅 Harvest: Aug 9 – Oct 4

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 Carlton County

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

Soil pH

Your soil pH (6.2–7.1) is within Zucchini's preferred range (6.0–7.5).

Soil Texture

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

Organic Matter

Organic matter is excellent (4.5%) — Zucchini will thrive.

How to Plant Zucchini

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

Succession Planting Zucchini

3
successive plantings in your 143-day season

Sow every 5.1 weeks. Last sowing by Aug 03 to harvest before frost.

Plant Water Budget

Plant needs
1.2″/week
Rainfall provides
1.0″/week
You supply
0.3″/week
Watering frequency Only during dry spells
Season total 361 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Zucchini

Zucchini needs approximately 1.2 inches of water per week (5.2" per month). Here's how your county's rainfall compares month by month.

Month Zucchini Needs Rainfall You Supplement Action
Jan 1.5" 0" ❄️ Dormant
Feb 1.5" 0" ❄️ Dormant
Mar 2.5" 0" ❄️ Dormant
Apr 3.1" 0" ❄️ Dormant
May 5.2" 3.4" 1.8" 💧 Light watering
Jun 5.2" 4.1" 1.1" 💧 Light watering
Jul 5.2" 3.5" 1.7" 💧 Light watering
Aug 5.2" 3.4" 1.8" 💧 Light watering
Sep 5.2" 2.7" 2.5" 💧 Light watering
Oct 5.2" 2.8" 2.4" 💧 Light watering
Nov 2.5" 0" ❄️ Dormant
Dec 1.9" 0" ❄️ Dormant

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

Zucchini 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.

Zucchini needs ~604 GDD — county provides 1,644 GDD Excellent fit

Zucchini Planting Timeline — Carlton County, MN

Zucchini Planting Calendar

Activity When Date Range
Start Indoors March 31 Mar 31 – Apr 14
Transplant Outdoors June 2 Jun 2 – Jun 16
Direct Sow May 26 May 26 – Jun 16
Harvest July 21 Jul 21 – Sep 15

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 Harvest
August Harvest
September Harvest
October
November
December
Share this guide:

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1.2"/week · Only during dry spells

📅 Days to Maturity

45–60 days

🧪 Soil pH

Needs 6–7.5 · Your soil: ideal

🗺️ USDA Zone

Zone 4a

📆 Growing Season

143 days in Carlton County

Growing Tips for Zucchini in Carlton County

Direct sow Zucchini outdoors after May 12 in Carlton County when soil has warmed and frost danger has passed.

Common pests for Zucchini 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 last frost. Harvest when fruits are 6-8 inches long for best flavor and texture. Check plants daily in summer as fruits can double in size overnight.

Companion Planting

Good Companions

Avoid Planting Near

  • Potatoes

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Zucchini in Carlton County, MN?

Carlton County is in Zone 4a with an average last frost of May 12. Plan your Zucchini planting based on this frost date — see the calendar above for exact timing.

What planting zone is Carlton County, MN?

Carlton County, Minnesota is in USDA Hardiness Zone 4a. The average last spring frost is May 12 and first fall frost is October 2.

🌱

Your Carlton County Garden Planner — Free

A 24-page printable planner built for Carlton 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.

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 Carlton 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.