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When to plant Arugula in Lanark, IL

Lanark's climate puts the Arugula spring window between April 8 and April 29. time plantings around the expected last-frost window for best survival. A second sowing from August 4 to August 18 extends the harvest into fall.

When to Plant Arugula in Lanark, IL

Carroll County, Illinois Zone 5a July

Your July gardening checklist

Your Carroll County, Illinois garden is entering a new phase. Here's what's on the schedule for July and why each task matters now.

Avg. last frost April 22
Avg. first frost October 13
Soil temp (4") 78°F
Watering Low
Pest pressure High
Daylight 14.8 hrs
  1. Pick arugula

    Taste as you pick. The first ripe produce is the best feedback loop you'll get all season.

To set up a strong August, finish these tasks
  • 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.

Lanark, Illinois is in USDA Zone 5a. The average last spring frost is April 22 and the first fall frost is October 13, giving you a growing season of approximately 174 days.

At an elevation of 778 feet, Carroll County receives approximately 39.3 inches of rainfall annually with predominantly silt loam soil. Summer highs average 84°F, so choose short-season varieties of Arugula to ensure they mature before fall.

Lanark, IL (Zone 5a) Moderate season
174 days
Last Spring Frost April 22
174 growing days
First Fall Frost October 13

Lanark Soil Profile

Soil Type

Silt Loam

Soil pH

5.9-6.8

Drainage

Well Drained

Arugula Planting Risk Windows

Early Start (70% safe) ✓ Fits season (78 days to spare)
Start indoors: Mar 12 Transplant: Apr 16 🍅 Harvest: May 21 – Jul 23
Recommended (50%) ✓ Fits season (76 days to spare)
Start indoors: Mar 18 Transplant: Apr 22 🍅 Harvest: May 27 – Jul 29
Safe Start (90%) ✓ Fits season (79 days to spare)
Start indoors: Mar 29 Transplant: May 3 🍅 Harvest: Jun 7 – Aug 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 Lanark

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

Soil pH

Your soil pH (5.9–6.8) overlaps with Arugula's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is excellent (4.8%) — 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

7
successive plantings in your 174-day season

Sow every 3.4 weeks. Last sowing by Aug 24 to harvest before frost.

For a dedicated fall crop, sow by Aug 04.

Arugula Water Budget

Plant needs
0.6″/week
Rainfall provides
1.0″/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 1.6" 0" ❄️ Dormant
Feb 1.6" 0" ❄️ Dormant
Mar 2.5" 0" ❄️ Dormant
Apr 2.6" 4.2" 0" ✅ Rainfall sufficient
May 2.6" 4.4" 0" ✅ Rainfall sufficient
Jun 2.6" 5" 0" ✅ Rainfall sufficient
Jul 2.6" 4.8" 0" ✅ Rainfall sufficient
Aug 2.6" 4.1" 0" ✅ Rainfall sufficient
Sep 2.6" 3.7" 0" ✅ Rainfall sufficient
Oct 2.6" 3" 0" ✅ Rainfall sufficient
Nov 2.4" 0" ❄️ Dormant
Dec 1.9" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Carroll 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 ~520 GDD — county provides 2,262 GDD Excellent fit

Arugula Planting Timeline — Lanark, IL

Arugula Planting Calendar

Activity When Date Range
Start Indoors March 18 Mar 18 – Apr 1
Transplant Outdoors April 22 Apr 22 – May 6
Direct Sow April 8 Apr 8 – Apr 29
Harvest May 27 May 27 – Jul 29
Fall Sowing August 4 Aug 4 – Aug 18

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

Month-by-Month Timeline

MonthActivities
January
February
March Start Indoors
April Start Indoors Transplant Outdoors Direct Sow
May Transplant Outdoors Harvest
June Harvest
July Harvest
August Fall Sowing
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 5a

📆 Growing Season

174 days in Carroll County

Growing Tips for Arugula in Lanark

Direct sow Arugula outdoors after April 22 in Carroll County when soil has warmed and frost danger has passed.

Your generous 174.0-day season in Carroll 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 →

When should I plant Arugula in Lanark, IL?

In Lanark, IL, plant Arugula after the last frost (around April 22) and before the first frost (around October 13). Best results when soil holds above 50°F.

What growing zone is Lanark, IL for Arugula?

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

Can Arugula grow in Lanark's climate?

Yes — Arugula grows well in Lanark's temperate climate. Lanark averages a 174-day frost-free season, with last frost around April 22 and first frost around October 13.

🌱

Your Carroll County Garden Planner — Free

A 22-page printable planner built for Carroll County (Zone 5a). 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 Carroll County, IL. Local conditions may vary. Last updated: July 2026.