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When to plant Squash (Summer) in St. Clair County, MI

Squash (Summer) planted in St. Clair County between May 4 and May 25 matures in 45–65 days — well before the October 27 first frost.

When to Plant Squash (Summer) in St. Clair County, MI

Summer squash includes zucchini, yellow crookneck, and pattypan varieties that are harvested young and tender. They are prolific producers in warm weather.

St. Clair County, Michigan is in USDA Zone 6a. The average last spring frost is April 27 and the first fall frost is October 27, giving you a growing season of approximately 183 days.

At an elevation of 1,065 feet, St. Clair County receives approximately 38.6 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85°F, providing good warmth for Squash (Summer) during the growing season.

St. Clair County, MI (Zone 6a) Moderate season
183 days
Last Spring Frost April 27
183 growing days
First Fall Frost October 27

St. Clair County Soil Profile

Soil Type

Silt Loam

Soil pH

6.1-7.2

Drainage

Well Drained

Monthly Watering Guide for Squash (Summer)

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

Month Squash (Summer) Needs Rainfall You Supplement Action
Jan 1.6" 0" ❄️ Dormant
Feb 1.6" 0" ❄️ Dormant
Mar 3" 0" ❄️ Dormant
Apr 4.3" 3.6" 0.7" 💧 Light watering
May 4.3" 3.9" 0.4" 💧 Light watering
Jun 4.3" 4.5" 0" ✅ Rainfall sufficient
Jul 4.3" 4.4" 0" ✅ Rainfall sufficient
Aug 4.3" 4.6" 0" ✅ Rainfall sufficient
Sep 4.3" 3.4" 0.9" 💧 Light watering
Oct 4.3" 3.3" 1" 💧 Light watering
Nov 2.7" 0" ❄️ Dormant
Dec 1.9" 0" ❄️ Dormant

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

Squash (Summer) Planting Timeline — St. Clair County, MI

Squash (Summer) Planting Calendar

Activity When Date Range
Start Indoors March 23 Mar 23 – Apr 6
Transplant Outdoors May 11 May 11 – May 25
Direct Sow May 4 May 4 – May 25
Harvest June 29 Jun 29 – Aug 31

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 Harvest
July Harvest
August Harvest
September
October
November
December

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

Moderate — regular watering

📅 Days to Maturity

45–65 days

🧪 Soil pH

Needs 6–7.5 · Your soil: N/A

🗺️ USDA Zone

Zone 6a

📆 Growing Season

183 days in St. Clair County

Growing Tips for St. Clair County

Direct sow after last frost on mounds. Harvest frequently when fruits are 6-8 inches for best texture. Check plants daily as they grow rapidly in summer heat.

Companion Planting

Good Companions

Avoid Planting Near

  • Potatoes

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Squash (Summer) in St. Clair County, MI?

St. Clair County is in Zone 6a with an average last frost of April 27. Plan your Squash (Summer) planting based on this frost date — see the calendar above for exact timing.

What planting zone is St. Clair County, MI?

St. Clair County, Michigan is in USDA Hardiness Zone 6a. The average last spring frost is April 27 and first fall frost is October 27.

When should I plant Squash (Summer) in St. Clair County, MI?

In St. Clair County, MI, plant Squash (Summer) after the last frost (around April 27) and before the first frost (around October 27). Best results when soil holds above 50°F.

What growing zone is St. Clair County, MI for Squash (Summer)?

St. Clair County sits in USDA Zone 6a. Squash (Summer) grows reliably in zones 3a through 11b, so it's a good fit here.

Can Squash (Summer) grow in St. Clair County's climate?

Yes — Squash (Summer) grows well in St. Clair County's temperate climate. St. Clair County averages a 183-day frost-free season, with last frost around April 27 and first frost around October 27.

🌱

Your St. Clair County Garden Planner — Free

A 22-page printable planner built for St. Clair 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 St. Clair County, MI. Local conditions may vary. Last updated: July 2026.

Sources & credits

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