Blog

When to Plant Cilantro in Rock County, MN

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.

Rock County, Minnesota is in USDA Zone 4b. The average last spring frost is May 2 and the first fall frost is October 2, giving you a growing season of approximately 153 days.

At an elevation of 916 feet, Rock County receives approximately 32.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 82ยฐF, so choose short-season varieties of Cilantro to ensure they mature before fall.

Rock County, MN (Zone 4b) Moderate season
153 days
Last Spring Frost May 2
153 growing days
First Fall Frost October 2

Rock County Soil Profile

Soil Type

Silt Loam

Soil pH

5.7-6.9

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (53 days to spare)
Start indoors: Mar 16 Transplant: Apr 20 🍅 Harvest: Jun 1 – Aug 3
Recommended (50%) ✓ Fits season (55 days to spare)
Start indoors: Mar 21 Transplant: Apr 25 🍅 Harvest: Jun 6 – Aug 8
Safe Start (90%) ✓ Fits season (52 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
0.9″/week
You supply
0.1″/week
Watering frequency Only during dry spells
Season total 181 gal / 100 sq ft
Drought risk

Water stress score is 6/10 โ€” consider drought-tolerant varieties and mulching

Cilantro needs ~575 GDD — county provides 1,759 GDD Excellent fit

Cilantro Planting Timeline โ€” Rock County, MN

Cilantro Planting Calendar

Activity When Date Range
Start Indoors March 21 Mar 21 โ€“ Apr 4
Transplant Outdoors April 25 Apr 25 โ€“ May 9
Direct Sow April 25 Apr 25 โ€“ May 16
Fall Sowing July 10 Jul 10 โ€“ Jul 24
Harvest June 6 Jun 6 โ€“ Aug 8

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

153 days

Growing Tips for Rock 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 Rock County, MN?

Rock County is in Zone 4b with an average last frost of May 2. Plan your Cilantro planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Rock County, MN?

Rock County, Minnesota is in USDA Hardiness Zone 4b. The average last spring frost is May 2 and first fall frost is October 2.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Rock County gardeners in Zone 4b organize planting dates, track what's growing, and never miss a planting window.

Get Your Free Garden Planner →

Free download. Plan your entire garden season in minutes.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Rock County, MN. Local conditions may vary. Last updated: April 2026.