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When to Plant Cilantro in Howard County, IA

Cilantro is a dual-purpose herb providing fresh leaves (cilantro) and dried seeds (coriander). It bolts quickly in heat, producing flowers beloved by beneficial insects.

Howard County, Iowa is in USDA Zone 4b. The average last spring frost is May 4 and the first fall frost is October 5, giving you a growing season of approximately 154 days.

At an elevation of 1,297 feet, Howard County receives approximately 39.7 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83ยฐF, so choose short-season varieties of Cilantro to ensure they mature before fall.

Howard County, IA (Zone 4b) Moderate season
154 days
Last Spring Frost May 4
154 growing days
First Fall Frost October 5

Howard County Soil Profile

Soil Type

Silt Loam

Soil pH

6.1-7.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (55 days to spare)
Start indoors: Mar 17 Transplant: Apr 21 🍅 Harvest: Jun 2 – Aug 4
Recommended (50%) ✓ Fits season (56 days to spare)
Start indoors: Mar 23 Transplant: Apr 27 🍅 Harvest: Jun 8 – Aug 10
Safe Start (90%) ✓ Fits season (55 days to spare)
Start indoors: Apr 4 Transplant: May 9 🍅 Harvest: Jun 20 – Aug 22

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
1.1″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Cilantro needs ~612 GDD — county provides 1,886 GDD Excellent fit

Cilantro Planting Timeline โ€” Howard County, IA

Cilantro Planting Calendar

Activity When Date Range
Start Indoors March 23 Mar 23 โ€“ Apr 6
Transplant Outdoors April 27 Apr 27 โ€“ May 11
Direct Sow April 27 Apr 27 โ€“ May 18
Fall Sowing July 13 Jul 13 โ€“ Jul 27
Harvest June 8 Jun 8 โ€“ Aug 10

Plant 0.5" deep ยท 8" apart ยท Rows 12" apart

Month-by-Month Timeline

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

Growing Conditions

Sun

Partial Shade (3-6 hours)

Water

Moderate โ€” regular watering

Days to Maturity

40โ€“60 days

Soil pH

6 โ€“ 7

USDA Zone

Zone 4b

Growing Season

154 days

Growing Tips for Howard County

Succession sow every 2-3 weeks. Provide afternoon shade in warm weather. Harvest leaves before flowering or allow some plants to go to seed for coriander and self-sowing.

Companion Planting

Good Companions

Avoid Planting Near

  • Fennel

Level Up Your Garden

Frequently Asked Questions

When should I plant Cilantro in Howard County, IA?

Howard County is in Zone 4b with an average last frost of May 4. Plan your Cilantro planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Howard County, IA?

Howard County, Iowa is in USDA Hardiness Zone 4b. The average last spring frost is May 4 and first fall frost is October 5.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Howard County gardeners in Zone 4b 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 Howard County, IA. Local conditions may vary. Last updated: April 2026.