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When to plant Arugula in Keweenaw County County,

Aim to plant Arugula in Keweenaw County County on or after May 5; the window stays open through May 26. Keweenaw County County's 135-day frost-free season gives you a single solid spring crop with a brief fall option. A second sowing from July 23 to August 6 extends the harvest into fall.

When to Plant Arugula in Keweenaw County, MI

Keweenaw County, Michigan Zone 5b June

Top priorities for Keweenaw County, Michigan gardeners in June

Here's what deserves your attention in Keweenaw County, Michigan this month. Everything below is tailored to Zone 5b and timed around your local frost dates.

Avg. last frost May 19
Avg. first frost October 1
Soil temp (4") 64°F
Watering Low
Pest pressure High
Daylight 15.7 hrs
  1. Sow arugula in trays indoors

    These need a head start before your last frost (May 19). Sow into cells now so you're ready to transplant in a few weeks.

  2. It's harvest week for arugula

    The more you pick, the more the plant produces. Letting fruit overripen tells the plant it's time to stop.

A few tasks this June that'll pay off in July
  • First harvests: arugula
  • Fall sowing: arugula

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Arugula is a fast-growing cool-season green with a peppery, nutty flavor. It is excellent in salads and can be harvested as baby greens or mature leaves.

Keweenaw County, Michigan is in USDA Zone 5b. The average last spring frost is May 19 and the first fall frost is October 1, giving you a growing season of approximately 135 days.

At an elevation of 1,035 feet, Keweenaw County receives approximately 40.9 inches of rainfall annually with predominantly silt loam soil. Summer highs average 81°F, so choose short-season varieties of Arugula to ensure they mature before fall.

Keweenaw County, MI (Zone 5b) Short season
135 days
Last Spring Frost May 19
135 growing days
First Fall Frost October 1
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Keweenaw County Soil Profile

Soil Type

Silt Loam

Soil pH

6.1-6.9

Drainage

Well Drained

Arugula Planting Risk Windows

Early Start (70% safe) ✓ Fits season (37 days to spare)
Start indoors: Apr 10 Transplant: May 15 🍅 Harvest: Jun 19 – Aug 21
Recommended (50%) ✓ Fits season (37 days to spare)
Start indoors: Apr 14 Transplant: May 19 🍅 Harvest: Jun 23 – Aug 25
Safe Start (90%) ✓ Fits season (36 days to spare)
Start indoors: Apr 30 Transplant: Jun 4 🍅 Harvest: Jul 9 – Sep 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 Keweenaw County

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

Soil pH

Your soil pH (6.1–6.9) is within Arugula's preferred range (6.0–7.0).

Soil Texture

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

Organic Matter

Organic matter is excellent (4.0%) — Arugula will thrive.

How to Plant Arugula

0.5"
Planting Depth
6"
Between Plants
12"
Between Rows

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

Succession Planting Arugula

5
successive plantings in your 135-day season

Sow every 3.4 weeks. Last sowing by Aug 12 to harvest before frost.

For a dedicated fall crop, sow by Jul 23.

Arugula Water Budget

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

Monthly Watering Guide for Arugula

Arugula needs approximately 0.6 inches of water per week (2.6" per month). Here's how your county's rainfall compares month by month.

Month Arugula Needs Rainfall You Supplement Action
Jan 1.7" 0" ❄️ Dormant
Feb 1.8" 0" ❄️ Dormant
Mar 2.6" 0" ❄️ Dormant
Apr 3.7" 0" ❄️ Dormant
May 2.6" 4.2" 0" ✅ Rainfall sufficient
Jun 2.6" 4.9" 0" ✅ Rainfall sufficient
Jul 2.6" 5" 0" ✅ Rainfall sufficient
Aug 2.6" 4.7" 0" ✅ Rainfall sufficient
Sep 2.6" 3.7" 0" ✅ Rainfall sufficient
Oct 2.6" 3.2" 0" ✅ Rainfall sufficient
Nov 2.9" 0" ❄️ Dormant
Dec 2.4" 0" ❄️ Dormant

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

Arugula 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.

Arugula needs ~430 GDD — county provides 1,451 GDD Excellent fit

Arugula Planting Timeline — Keweenaw County, MI

Arugula Planting Calendar

Activity When Date Range
Start Indoors April 14 Apr 14 – Apr 28
Transplant Outdoors May 19 May 19 – Jun 2
Direct Sow May 5 May 5 – May 26
Harvest June 23 Jun 23 – Aug 25
Fall Sowing July 23 Jul 23 – Aug 6

Plant 0.5" deep · 6" apart · Rows 12" apart

Month-by-Month Timeline

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

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

0.6"/week · Natural rainfall sufficient

📅 Days to Maturity

30–50 days

🧪 Soil pH

Needs 6–7 · Your soil: ideal

🗺️ USDA Zone

Zone 5b

📆 Growing Season

135 days in Keweenaw County

Growing Tips for Arugula in Keweenaw County

Direct sow Arugula outdoors after May 19 in Keweenaw County when soil has warmed and frost danger has passed.

Your generous 135.0-day season in Keweenaw County allows multiple plantings of Arugula. Sow every 15.0 days for continuous harvest.

Common pests for Arugula in this region include cabbage worm and flea beetles. Use row covers early in the season and inspect plants weekly.

General growing tips

Sow seeds directly every 2-3 weeks for continuous harvest. Provide afternoon shade in warm weather to prevent bolting. Harvest outer leaves first to extend production.

Companion Planting

Good Companions

Avoid Planting Near

  • Strawberries

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Arugula in Keweenaw County, MI?

Keweenaw County is in Zone 5b with an average last frost of May 19. Plan your Arugula planting based on this frost date — see the calendar above for exact timing.

What planting zone is Keweenaw County, MI?

Keweenaw County, Michigan is in USDA Hardiness Zone 5b. The average last spring frost is May 19 and first fall frost is October 1.

When should I plant Arugula in Keweenaw County County, ?

In Keweenaw County County, , plant Arugula after the last frost (around May 19) and before the first frost (around October 1). Best results when soil holds above 50°F.

What growing zone is Keweenaw County County, for Arugula?

Keweenaw County County sits in USDA Zone 5b. Arugula grows reliably in zones 3a through 11b, so it's a good fit here.

Can Arugula grow in Keweenaw County County's climate?

Yes — Arugula grows well in Keweenaw County County's temperate climate. Keweenaw County County averages a 135-day frost-free season, with last frost around May 19 and first frost around October 1.

🌱

Your Keweenaw County Garden Planner — Free

A 22-page printable planner built for Keweenaw County (Zone 5b). 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 Keweenaw County, MI. Local conditions may vary. Last updated: June 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.