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When to Plant Arugula in Knox County, IN

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.

Knox County, Indiana is in USDA Zone 6a. The average last spring frost is April 10 and the first fall frost is October 23, giving you a growing season of approximately 196 days.

At an elevation of 735 feet, Knox County receives approximately 38.9 inches of rainfall annually with predominantly silt loam soil. Summer highs average 91ยฐF, providing good warmth for Arugula during the growing season.

Knox County, IN (Zone 6a) Moderate season
196 days
Last Spring Frost April 10
196 growing days
First Fall Frost October 23

Knox County Soil Profile

Soil Type

Silt Loam

Soil pH

6-7.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (99 days to spare)
Start indoors: Mar 1 Transplant: Apr 5 🍅 Harvest: May 10 – Jul 12
Recommended (50%) ✓ Fits season (98 days to spare)
Start indoors: Mar 6 Transplant: Apr 10 🍅 Harvest: May 15 – Jul 17
Safe Start (90%) ✓ Fits season (98 days to spare)
Start indoors: Mar 20 Transplant: Apr 24 🍅 Harvest: May 29 – Jul 31

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.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.8″/week
You supply
0.2″/week
Watering frequency Only during dry spells
Season total 290 gal / 100 sq ft
Arugula needs ~730 GDD — county provides 3,577 GDD Excellent fit

Arugula Planting Timeline โ€” Knox County, IN

Arugula Planting Calendar

Activity When Date Range
Start Indoors March 6 Mar 6 โ€“ Mar 20
Transplant Outdoors April 10 Apr 10 โ€“ Apr 24
Direct Sow March 27 Mar 27 โ€“ Apr 17
Fall Sowing August 14 Aug 14 โ€“ Aug 28
Harvest May 15 May 15 โ€“ Jul 17

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

Month-by-Month Timeline

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

Growing Conditions

Sun

Partial Shade (3-6 hours)

Water

Moderate โ€” regular watering

Days to Maturity

30โ€“50 days

Soil pH

6 โ€“ 7

USDA Zone

Zone 6a

Growing Season

196 days

Growing Tips for Knox County

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

Level Up Your Garden

Frequently Asked Questions

When should I plant Arugula in Knox County, IN?

Knox County is in Zone 6a with an average last frost of April 10. Plan your Arugula planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Knox County, IN?

Knox County, Indiana is in USDA Hardiness Zone 6a. The average last spring frost is April 10 and first fall frost is October 23.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Knox County gardeners in Zone 6a organize planting dates, track what's growing, and never miss a planting window.

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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 Knox County, IN. Local conditions may vary. Last updated: April 2026.