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When to plant Arugula in Cook County, MN

The best window to plant Arugula in Cook County, is May 13–June 3, when soil warms to 50°F. Last frost typically hits May 20; first frost September 29. A second sowing from July 7 to July 21 extends the harvest into fall.

When to Plant Arugula in Cook County, MN

Cook County, Minnesota Zone 3b July

July in the garden — Cook County, Minnesota

Each item below is timed to Cook County, Minnesota's frost dates and soil temperatures. Skip nothing, stress about nothing.

Avg. last frost May 20
Avg. first frost September 29
Soil temp (4") 69°F
Watering Low
Pest pressure Moderate
Daylight 15.4 hrs
  1. Start arugula under lights

    Give them 6–8 weeks indoors before the last frost and you'll transplant into warm soil with seedlings that are already leaping.

  2. Pick arugula

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

  3. Sow arugula for an autumn harvest

    Keep young seedlings shaded and moist in summer heat. A row of taller crops works as natural shade.

Before August arrives, get these ready
  • First harvests: 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.

Cook County, Minnesota is in USDA Zone 3b. The average last spring frost is May 20 and the first fall frost is September 29, giving you a growing season of approximately 132 days.

At an elevation of 1,068 feet, Cook County receives approximately 34.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 80°F, so choose short-season varieties of Arugula to ensure they mature before fall.

Cook County, MN (Zone 3b) Short season
132 days
Last Spring Frost May 20
132 growing days
First Fall Frost September 29

Cook County Soil Profile

Soil Type

Silt Loam

Soil pH

6.1-7.1

Drainage

Well Drained

Arugula Planting Risk Windows

Early Start (70% safe) ✓ Fits season (34 days to spare)
Start indoors: Apr 3 Transplant: May 15 🍅 Harvest: Jun 19 – Aug 21
Recommended (50%) ✓ Fits season (34 days to spare)
Start indoors: Apr 8 Transplant: May 20 🍅 Harvest: Jun 24 – Aug 26
Safe Start (90%) ✓ Fits season (37 days to spare)
Start indoors: Apr 19 Transplant: May 31 🍅 Harvest: Jul 5 – Sep 6

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 Cook County

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

Soil pH

Your soil pH (6.1–7.1) overlaps with Arugula's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is excellent (4.4%) — Arugula will thrive.

How to Plant Arugula

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

Fall planting: Sow 12 weeks before your first frost date for a fall harvest.

Succession Planting Arugula

5
successive plantings in your 132-day season

Sow every 3.4 weeks. Last sowing by Aug 10 to harvest before frost.

For a dedicated fall crop, sow by Jul 07.

Arugula Water Budget

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

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

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 1.4" 0" ❄️ Dormant
Feb 1.6" 0" ❄️ Dormant
Mar 2.5" 0" ❄️ Dormant
Apr 3.5" 0" ❄️ Dormant
May 2.6" 3.4" 0" ✅ Rainfall sufficient
Jun 2.6" 4.7" 0" ✅ Rainfall sufficient
Jul 2.6" 3.9" 0" ✅ Rainfall sufficient
Aug 2.6" 3" 0" ✅ Rainfall sufficient
Sep 2.6" 3.2" 0" ✅ Rainfall sufficient
Oct 2.7" 0" ❄️ Dormant
Nov 2.5" 0" ❄️ Dormant
Dec 2" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Cook 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 ~400 GDD — county provides 1,320 GDD Excellent fit

Arugula Planting Timeline — Cook County, MN

Arugula Planting Calendar

Activity When Date Range
Start Indoors April 8 Apr 8 – Apr 22
Transplant Outdoors May 20 May 20 – Jun 3
Direct Sow May 13 May 13 – Jun 3
Harvest June 24 Jun 24 – Aug 26
Fall Sowing July 7 Jul 7 – Jul 21

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 Direct Sow Harvest
July Fall Sowing Harvest
August Harvest
September
October
November
December

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: acceptable

🗺️ USDA Zone

Zone 3b

📆 Growing Season

132 days in Cook County

Growing Tips for Arugula in Cook County

Direct sow Arugula outdoors after May 20 in Cook County when soil has warmed and frost danger has passed.

Your generous 132.0-day season in Cook 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 Cook County, MN?

Cook County is in Zone 3b with an average last frost of May 20. Plan your Arugula planting based on this frost date — see the calendar above for exact timing.

What planting zone is Cook County, MN?

Cook County, Minnesota is in USDA Hardiness Zone 3b. The average last spring frost is May 20 and first fall frost is September 29.

When should I plant Arugula in Cook County, MN?

In Cook County, MN, plant Arugula after the last frost (around May 20) and before the first frost (around September 29). Best results when soil holds above 50°F.

What growing zone is Cook County, MN for Arugula?

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

Can Arugula grow in Cook County's climate?

Yes — Arugula grows well in Cook County's temperate climate. Cook County averages a 132-day frost-free season, with last frost around May 20 and first frost around September 29.

🌱

Your Cook County Garden Planner — Free

A 22-page printable planner built for Cook County (Zone 3b). 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 Cook County, MN. Local conditions may vary. Last updated: July 2026.

Sources & credits

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