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When to Plant Black Beans in Ontonagon County, MI

Ontonagon County, Michigan Zone 4b May

Top priorities for Ontonagon County, Michigan gardeners in May

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

Avg. last frost May 22
Avg. first frost September 28
Soil temp (4") 54°F
Watering Low
Pest pressure Low
Daylight 14.8 hrs
To set up a strong June, finish these tasks
  • Direct-sowing: black beans

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Black beans are a warm-season legume producing small, dark, protein-rich beans that are a staple in Latin American and Caribbean cuisines.

Ontonagon County, Michigan is in USDA Zone 4b. The average last spring frost is May 22 and the first fall frost is September 28, giving you a growing season of approximately 129 days.

At an elevation of 502 feet, Ontonagon County receives approximately 42 inches of rainfall annually with predominantly silt loam soil. Summer highs average 80°F, so choose short-season varieties of Black Beans to ensure they mature before fall.

Ontonagon County, MI (Zone 4b) Short season
129 days
Last Spring Frost May 22
129 growing days
First Fall Frost September 28
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Ontonagon County Soil Profile

Soil Type

Silt Loam

Soil pH

6.2-7.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Transplant: May 18 🍅 Harvest: Aug 17 – Oct 5
Recommended (50%) ✗ May not fit
Transplant: May 22 🍅 Harvest: Aug 21 – Oct 9
Safe Start (90%) ✗ May not fit
Transplant: Jun 6 🍅 Harvest: Sep 5 – Oct 24

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 Ontonagon County

How your county's soil matches Black Beans's growing requirements.

Soil pH

Your soil pH (6.2–7.2) is within Black Beans's preferred range (6.0–7.5).

Soil Texture

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

Organic Matter

Organic matter is excellent (5.1%) — Black Beans will thrive.

How to Plant Black Beans

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

Plant Water Budget

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

Monthly Watering Guide for Black Beans

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

Month Black Beans Needs Rainfall You Supplement Action
Jan 2" 0" ❄️ Dormant
Feb 2.1" 0" ❄️ Dormant
Mar 2.8" 0" ❄️ Dormant
Apr 4.4" 0" ❄️ Dormant
May 4.3" 4.8" 0" ✅ Rainfall sufficient
Jun 4.3" 5.2" 0" ✅ Rainfall sufficient
Jul 4.3" 4.3" 0" ✅ Rainfall sufficient
Aug 4.3" 4.2" 0.1" 💧 Light watering
Sep 4.3" 3.5" 0.8" 💧 Light watering
Oct 3.6" 0" ❄️ Dormant
Nov 2.6" 0" ❄️ Dormant
Dec 2.4" 0" ❄️ Dormant

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

Black Beans 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.

Black Beans needs ~1,050 GDD — county provides 1,290 GDD Good fit

Black Beans Planting Timeline — Ontonagon County, MI

Black Beans Planting Calendar

Activity When Date Range
Direct Sow June 5 Jun 5 – Jun 26
Harvest September 4 Sep 4 – Oct 23

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

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Natural rainfall sufficient

📅 Days to Maturity

90–120 days

🧪 Soil pH

Needs 6–7.5 · Your soil: ideal

🗺️ USDA Zone

Zone 4b

📆 Growing Season

129 days in Ontonagon County

Growing Tips for Black Beans in Ontonagon County

Direct sow Black Beans outdoors after May 22 in Ontonagon County when soil has warmed and frost danger has passed.

Your 129.0-day growing season in Ontonagon County is tight for Black Beans (90.0-120.0 days to maturity). Start indoors and choose early-maturing varieties.

Common pests for Black Beans 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 last frost. Provide support for climbing varieties. Allow pods to dry fully on the vine before harvesting. Thresh dried pods by hand or in a pillowcase.

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 Black Beans in Ontonagon County, MI?

Ontonagon County is in Zone 4b with an average last frost of May 22. Plan your Black Beans planting based on this frost date — see the calendar above for exact timing.

What planting zone is Ontonagon County, MI?

Ontonagon County, Michigan is in USDA Hardiness Zone 4b. The average last spring frost is May 22 and first fall frost is September 28.

🌱

Your Ontonagon County Garden Planner — Free

A 24-page printable planner built for Ontonagon County (Zone 4b). 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 Ontonagon 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.