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When to Plant Soybeans in Lapeer County, MI

Lapeer County, Michigan Zone 6a May

This month in Lapeer County, Michigan

May rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Lapeer County, Michigan.

Avg. last frost April 30
Avg. first frost October 19
Soil temp (4") 59°F
Watering Low
Pest pressure Low
Daylight 14.5 hrs
  1. Plant soybeans from seed, right in the garden

    Mark the row. Birds and stray feet both have opinions about unmarked beds.

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Soybeans (edamame) are a high-protein legume that fixes nitrogen in the soil. Fresh green soybeans harvested at the edamame stage are a nutritious snack.

Lapeer County, Michigan is in USDA Zone 6a. The average last spring frost is April 30 and the first fall frost is October 19, giving you a growing season of approximately 172 days.

At an elevation of 1,011 feet, Lapeer County receives approximately 36.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 84°F, so choose short-season varieties of Soybeans to ensure they mature before fall.

Lapeer County, MI (Zone 6a) Moderate season
172 days
Last Spring Frost April 30
172 growing days
First Fall Frost October 19
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Lapeer County Soil Profile

Soil Type

Silt Loam

Soil pH

5.8-7.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (26 days to spare)
Transplant: Apr 27 🍅 Harvest: Jul 20 – Sep 14
Recommended (50%) ✓ Fits season (32 days to spare)
Transplant: Apr 30 🍅 Harvest: Jul 23 – Sep 17
Safe Start (90%) ✓ Fits season (21 days to spare)
Transplant: May 23 🍅 Harvest: Aug 15 – 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 Lapeer County

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

Soil pH

Your soil pH (5.8–7.2) overlaps with Soybeans's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Drainage

Drainage is adequate for Soybeans.

Organic Matter

Organic matter is moderate (3.9%). Annual compost additions will help Soybeans.

How to Plant Soybeans

1"
Planting Depth
15"
Between Plants
24"
Between Rows

Succession Planting Soybeans

2
successive plantings in your 172-day season

Sow every 9.1 weeks. Last sowing by Jun 21 to harvest before frost.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.9″/week
You supply
0.4″/week
Watering frequency 1-2 times/week
Season total 629 gal / 100 sq ft

Monthly Watering Guide for Soybeans

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

Month Soybeans Needs Rainfall You Supplement Action
Jan 1.4" 0" ❄️ Dormant
Feb 1.5" 0" ❄️ Dormant
Mar 2.4" 0" ❄️ Dormant
Apr 4.3" 3.2" 1.1" 💧 Light watering
May 4.3" 4.4" 0" ✅ Rainfall sufficient
Jun 4.3" 5.1" 0" ✅ Rainfall sufficient
Jul 4.3" 4.3" 0" ✅ Rainfall sufficient
Aug 4.3" 3.4" 0.9" 💧 Light watering
Sep 4.3" 3.7" 0.6" 💧 Light watering
Oct 4.3" 2.7" 1.6" 💧 Light watering
Nov 2.3" 0" ❄️ Dormant
Dec 2" 0" ❄️ Dormant

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

Soybeans 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.

Soybeans needs ~1,300 GDD — county provides 2,236 GDD Excellent fit

Soybeans Planting Timeline — Lapeer County, MI

Soybeans Planting Calendar

Activity When Date Range
Direct Sow May 7 May 7 – May 28
Harvest July 30 Jul 30 – Sep 24

Plant 1" deep · 15" apart · Rows 24" apart

Month-by-Month Timeline

MonthActivities
January
February
March
April
May Direct Sow
June
July Harvest
August Harvest
September Harvest
October
November
December
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Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · 1-2 times/week

📅 Days to Maturity

80–120 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 6a

📆 Growing Season

172 days in Lapeer County

Growing Tips for Soybeans in Lapeer County

Direct sow Soybeans outdoors after April 30 in Lapeer County when soil has warmed and frost danger has passed.

Common pests for Soybeans in this region include bean beetles and aphids. Use row covers early in the season and inspect plants weekly.

General growing tips

Direct sow after soil warms to 60F. Plant in blocks rather than rows for better pollination. Harvest for edamame when pods are plump and bright green.

Companion Planting

Good Companions

Avoid Planting Near

  • Onion
  • Garlic

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Soybeans in Lapeer County, MI?

Lapeer County is in Zone 6a with an average last frost of April 30. Plan your Soybeans planting based on this frost date — see the calendar above for exact timing.

What planting zone is Lapeer County, MI?

Lapeer County, Michigan is in USDA Hardiness Zone 6a. The average last spring frost is April 30 and first fall frost is October 19.

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Your Lapeer County Garden Planner — Free

A 24-page printable planner built for Lapeer 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 Lapeer County, MI. 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.