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When to Plant Onion in Benzie County, MI

Benzie County, Michigan Zone 6b May

Your May gardening checklist

Your garden in Benzie County, Michigan is working on a schedule, even when you're not. Here's where you should be this May.

Avg. last frost May 12
Avg. first frost October 13
Soil temp (4") 58°F
Watering Moderate
Pest pressure Low
Daylight 14.6 hrs
  1. Move onion into the garden

    Bring a watering can to the bed. Each transplant gets a drink the moment it's in the ground, not ten minutes later.

June will be here before you know it — start on
  • Starting indoors: onion

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Onions are a fundamental kitchen staple available in yellow, white, and red varieties. Choose long-day, short-day, or intermediate types based on your latitude.

Benzie County, Michigan is in USDA Zone 6b. The average last spring frost is May 12 and the first fall frost is October 13, giving you a growing season of approximately 154 days.

At an elevation of 1,075 feet, Benzie County receives approximately 32.9 inches of rainfall annually with predominantly silt loam soil. Summer highs average 87°F, providing good warmth for Onion during the growing season.

Benzie County, MI (Zone 6b) Moderate season
154 days
Last Spring Frost May 12
154 growing days
First Fall Frost October 13

Benzie County Soil Profile

Soil Type

Silt Loam

Soil pH

6-6.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (13 days to spare)
Start indoors: Mar 30 Transplant: May 4 🍅 Harvest: Aug 3 – Sep 21
Recommended (50%) ✓ Fits season (14 days to spare)
Start indoors: Apr 7 Transplant: May 12 🍅 Harvest: Aug 11 – Sep 29
Safe Start (90%) ✓ Fits season (23 days to spare)
Start indoors: Apr 17 Transplant: May 22 🍅 Harvest: Aug 21 – Oct 9

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 Benzie County

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

Soil pH

Your soil pH (6.0–6.7) is within Onion's preferred range (6.0–7.0).

Soil Texture

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

Organic Matter

Organic matter is excellent (4.2%) — Onion will thrive.

How to Plant Onion

1"
Planting Depth
6"
Between Plants
12"
Between Rows

Fall planting: Sow 10 weeks before your first frost date for a fall harvest.

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 169 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Onion

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

Month Onion Needs Rainfall You Supplement Action
Jan 1.4" 0" ❄️ Dormant
Feb 1.3" 0" ❄️ Dormant
Mar 2.5" 0" ❄️ Dormant
Apr 3.4" 0" ❄️ Dormant
May 4.3" 3.7" 0.6" 💧 Light watering
Jun 4.3" 4.4" 0" ✅ Rainfall sufficient
Jul 4.3" 4" 0.3" 💧 Light watering
Aug 4.3" 3" 1.3" 💧 Light watering
Sep 4.3" 2.9" 1.4" 💧 Light watering
Oct 4.3" 2.6" 1.7" 💧 Light watering
Nov 2" 0" ❄️ Dormant
Dec 1.6" 0" ❄️ Dormant

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

Onion 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.

Onion needs ~1,601 GDD — county provides 2,348 GDD Excellent fit

Onion Planting Timeline — Benzie County, MI

Onion Planting Calendar

Activity When Date Range
Start Indoors April 7 Apr 7 – Apr 21
Transplant Outdoors May 12 May 12 – May 26
Direct Sow April 28 Apr 28 – May 19
Harvest August 11 Aug 11 – Sep 29
Fall Sowing August 4 Aug 4 – Aug 18

Plant 1" deep · 6" apart · Rows 12" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Only during dry spells

📅 Days to Maturity

90–120 days

🧪 Soil pH

Needs 6–7 · Your soil: ideal

🗺️ USDA Zone

Zone 6b

📆 Growing Season

154 days in Benzie County

Growing Tips for Onion in Benzie County

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

Common pests for Onion in this region include onion maggots and thrips. Use row covers early in the season and inspect plants weekly.

General growing tips

Start seeds indoors 8-10 weeks before transplanting. Match day-length type to your latitude. Stop watering when tops begin to fall over and cure bulbs for 2-3 weeks before storage.

Companion Planting

Good Companions

Avoid Planting Near

  • Peas
  • Green Beans
  • Asparagus

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Onion in Benzie County, MI?

Benzie County is in Zone 6b with an average last frost of May 12. Plan your Onion planting based on this frost date — see the calendar above for exact timing.

What planting zone is Benzie County, MI?

Benzie County, Michigan is in USDA Hardiness Zone 6b. The average last spring frost is May 12 and first fall frost is October 13.

🌱

Your Benzie County Garden Planner — Free

A 24-page printable planner built for Benzie County (Zone 6b). 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 Benzie 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.