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When to Plant Arugula in Hardin County, OH

Hardin County, Ohio Zone 6a May

Hardin County, Ohio gardeners: here's your May plan

We've pulled the most time-sensitive tasks for Hardin County, Ohio this May and put them front and centre. Tackle them in order.

Avg. last frost April 26
Avg. first frost October 20
Soil temp (4") 59°F
Watering Moderate
Pest pressure Low
Daylight 14.3 hrs
  1. Begin indoor sowing: arugula

    Label every cell. You will absolutely forget which is which otherwise.

  2. Collect arugula at their peak

    If you can't use it all right away, check the food-preservation section of your planner.

Before June 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.

Hardin County, Ohio is in USDA Zone 6a. The average last spring frost is April 26 and the first fall frost is October 20, giving you a growing season of approximately 177 days.

At an elevation of 935 feet, Hardin County receives approximately 30.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85°F, providing good warmth for Arugula during the growing season.

Hardin County, OH (Zone 6a) Moderate season
177 days
Last Spring Frost April 26
177 growing days
First Fall Frost October 20

Hardin County Soil Profile

Soil Type

Silt Loam

Soil pH

6.3-6.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (83 days to spare)
Start indoors: Mar 14 Transplant: Apr 18 🍅 Harvest: May 23 – Jul 25
Recommended (50%) ✓ Fits season (79 days to spare)
Start indoors: Mar 22 Transplant: Apr 26 🍅 Harvest: May 31 – Aug 2
Safe Start (90%) ✓ Fits season (75 days to spare)
Start indoors: Apr 7 Transplant: May 12 🍅 Harvest: Jun 16 – Aug 18

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 Hardin County

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

Soil pH

Your soil pH (6.3–6.8) is within Arugula's preferred range (6.0–7.0).

Soil Texture

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

Organic Matter

Organic matter is moderate (4.0%). Annual compost additions will help Arugula.

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 177-day season

Sow every 3.4 weeks. Last sowing by Aug 31 to harvest before frost.

For a dedicated fall crop, sow by Aug 11.

Plant Water Budget

Plant needs
0.6″/week
Rainfall provides
0.7″/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 1.4" 0" ❄️ Dormant
Feb 1.4" 0" ❄️ Dormant
Mar 2.1" 0" ❄️ Dormant
Apr 2.6" 3.1" 0" ✅ Rainfall sufficient
May 2.6" 3.5" 0" ✅ Rainfall sufficient
Jun 2.6" 3.9" 0" ✅ Rainfall sufficient
Jul 2.6" 3.1" 0" ✅ Rainfall sufficient
Aug 2.6" 3.5" 0" ✅ Rainfall sufficient
Sep 2.6" 2.9" 0" ✅ Rainfall sufficient
Oct 2.6" 2.2" 0.4" 💧 Light watering
Nov 1.8" 0" ❄️ Dormant
Dec 1.4" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Hardin 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 ~550 GDD — county provides 2,433 GDD Excellent fit

Arugula Planting Timeline — Hardin County, OH

Arugula Planting Calendar

Activity When Date Range
Start Indoors March 22 Mar 22 – Apr 5
Transplant Outdoors April 26 Apr 26 – May 10
Direct Sow April 12 Apr 12 – May 3
Harvest May 31 May 31 – Aug 2
Fall Sowing August 11 Aug 11 – Aug 25

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 Direct Sow Harvest
June Harvest
July Harvest
August Fall Sowing 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: ideal

🗺️ USDA Zone

Zone 6a

📆 Growing Season

177 days in Hardin County

Growing Tips for Arugula in Hardin County

Direct sow Arugula outdoors after April 26 in Hardin County when soil has warmed and frost danger has passed.

Your generous 177.0-day season in Hardin 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 Hardin County, OH?

Hardin County is in Zone 6a with an average last frost of April 26. Plan your Arugula planting based on this frost date — see the calendar above for exact timing.

What planting zone is Hardin County, OH?

Hardin County, Ohio is in USDA Hardiness Zone 6a. The average last spring frost is April 26 and first fall frost is October 20.

🌱

Your Hardin County Garden Planner — Free

A 24-page printable planner built for Hardin County (Zone 6a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

Instant PDF download. No spam, unsubscribe any time.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Hardin County, OH. 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.