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When to Plant Squash (Summer) in Ionia County, MI

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

Ionia County, Michigan is in USDA Zone 5b. The average last spring frost is May 1 and the first fall frost is October 10, giving you a growing season of approximately 162 days.

At an elevation of 705 feet, Ionia County receives approximately 35.9 inches of rainfall annually with predominantly silt loam soil. Summer highs average 87ยฐF, providing good warmth for Squash (Summer) during the growing season.

Ionia County, MI (Zone 5b) Moderate season
162 days
Last Spring Frost May 1
162 growing days
First Fall Frost October 10

Ionia County Soil Profile

Soil Type

Silt Loam

Soil pH

6.1-6.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (34 days to spare)
Start indoors: Mar 24 Transplant: May 12 🍅 Harvest: Jun 30 – Sep 1
Recommended (50%) ✓ Fits season (36 days to spare)
Start indoors: Mar 27 Transplant: May 15 🍅 Harvest: Jul 3 – Sep 4
Safe Start (90%) ✓ Fits season (32 days to spare)
Start indoors: Apr 15 Transplant: Jun 3 🍅 Harvest: Jul 22 – Sep 23

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.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.9″/week
You supply
0.1″/week
Watering frequency Only during dry spells
Season total 120 gal / 100 sq ft
Drought risk

Water stress score is 6/10 โ€” consider drought-tolerant varieties and mulching

Squash (Summer) needs ~839 GDD — county provides 2,470 GDD Excellent fit

Squash (Summer) Planting Timeline โ€” Ionia County, MI

Squash (Summer) Planting Calendar

Activity When Date Range
Start Indoors March 27 Mar 27 โ€“ Apr 10
Transplant Outdoors May 15 May 15 โ€“ May 29
Direct Sow May 8 May 8 โ€“ May 29
Harvest July 3 Jul 3 โ€“ Sep 4

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

Month-by-Month Timeline

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

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Moderate โ€” regular watering

Days to Maturity

45โ€“65 days

Soil pH

6 โ€“ 7.5

USDA Zone

Zone 5b

Growing Season

162 days

Growing Tips for Ionia 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

Level Up Your Garden

Frequently Asked Questions

When should I plant Squash (Summer) in Ionia County, MI?

Ionia County is in Zone 5b with an average last frost of May 1. Plan your Squash (Summer) planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Ionia County, MI?

Ionia County, Michigan is in USDA Hardiness Zone 5b. The average last spring frost is May 1 and first fall frost is October 10.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Ionia County gardeners in Zone 5b organize planting dates, track what's growing, and never miss a planting window.

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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 Ionia County, MI. Local conditions may vary. Last updated: April 2026.