When to plant Cilantro in Johnson County, IA
For Cilantro in Johnson County, the safe spring window opens around April 10 and closes around May 1. Last expected frost is April 24, first fall frost October 11, giving a 170-day growing season. A second sowing from August 2 to August 16 extends the harvest into fall.
When to Plant Cilantro in Johnson County, IA
June in the garden — Johnson County, Iowa
June rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Johnson County, Iowa.
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Pick cilantro
If you can't use it all right away, check the food-preservation section of your planner.
A few tasks this June that'll pay off in July
- First harvests: cilantro
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.
Johnson County, Iowa is in USDA Zone 5b. The average last spring frost is April 24 and the first fall frost is October 11, giving you a growing season of approximately 170 days.
At an elevation of 1,204 feet, Johnson County receives approximately 40.7 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85°F, providing good warmth for Cilantro during the growing season.
Johnson County Soil Profile
Soil Type
Silt Loam
Soil pH
6.2-7.3
Drainage
Well Drained
Cilantro Planting Risk Windows
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 Johnson County
How your county's soil matches Cilantro's growing requirements.
Soil pH
Your soil pH (6.2–7.3) overlaps with Cilantro's range (6.0–7.0), though not a perfect match.
Soil Texture
The silt loam soil in Johnson County is excellent for Cilantro — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (3.9%). Annual compost additions will help Cilantro.
How to Plant Cilantro
Fall planting: Sow 10 weeks before your first frost date for a fall harvest.
Succession Planting Cilantro
Sow every 4.6 weeks. Last sowing by Aug 12 to harvest before frost.
For a dedicated fall crop, sow by Aug 02.
Cilantro Water Budget
Monthly Watering Guide for Cilantro
Cilantro needs approximately 0.5 inches of water per week (2.2" per month). Here's how your county's rainfall compares month by month.
| Month | Cilantro Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1.8" | 0" | ❄️ Dormant |
| Feb | — | 2" | 0" | ❄️ Dormant |
| Mar | — | 2.8" | 0" | ❄️ Dormant |
| Apr | 2.2" | 3.7" | 0" | ✅ Rainfall sufficient |
| May | 2.2" | 4.8" | 0" | ✅ Rainfall sufficient |
| Jun | 2.2" | 5.4" | 0" | ✅ Rainfall sufficient |
| Jul | 2.2" | 4.5" | 0" | ✅ Rainfall sufficient |
| Aug | 2.2" | 3.6" | 0" | ✅ Rainfall sufficient |
| Sep | 2.2" | 3.6" | 0" | ✅ Rainfall sufficient |
| Oct | 2.2" | 3.4" | 0" | ✅ Rainfall sufficient |
| Nov | — | 2.9" | 0" | ❄️ Dormant |
| Dec | — | 2.3" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Johnson County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Cilantro 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.
Cilantro Planting Timeline — Johnson County, IA
Cilantro Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 20 | Mar 20 – Apr 3 |
| Transplant Outdoors | April 17 | Apr 17 – May 1 |
| Direct Sow | April 10 | Apr 10 – May 1 |
| Harvest | May 29 | May 29 – Jul 31 |
| Fall Sowing | August 2 | Aug 2 – Aug 16 |
Plant 0.5" deep · 8" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| 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 |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Partial Shade (3-6 hours)
💧 Water
0.5"/week · Natural rainfall sufficient
📅 Days to Maturity
40–60 days
🧪 Soil pH
Needs 6–7 · Your soil: acceptable
🗺️ USDA Zone
Zone 5b
📆 Growing Season
170 days in Johnson County
Growing Tips for Cilantro in Johnson County
Direct sow Cilantro outdoors after April 24 in Johnson County when soil has warmed and frost danger has passed.
Your generous 170.0-day season in Johnson County allows multiple plantings of Cilantro. Sow every 20.0 days for continuous harvest.
Common pests for Cilantro in this region include carrot rust fly and parsleyworm. Use row covers early in the season and inspect plants weekly.
General growing tips
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
Check more plant combinations with our Companion Planting Checker →
Cilantro in Other Locations
Frequently Asked Questions
When should I plant Cilantro in Johnson County, IA?
Johnson County is in Zone 5b with an average last frost of April 24. Plan your Cilantro planting based on this frost date — see the calendar above for exact timing.
What planting zone is Johnson County, IA?
Johnson County, Iowa is in USDA Hardiness Zone 5b. The average last spring frost is April 24 and first fall frost is October 11.
When should I plant Cilantro in Johnson County, IA?
In Johnson County, IA, plant Cilantro after the last frost (around April 24) and before the first frost (around October 11). Best results when soil holds above 50°F.
What growing zone is Johnson County, IA for Cilantro?
Johnson County sits in USDA Zone 5b. Cilantro grows reliably in zones 2a through 11b, so it's a good fit here.
Can Cilantro grow in Johnson County's climate?
Yes — Cilantro grows well in Johnson County's temperate climate. Johnson County averages a 170-day frost-free season, with last frost around April 24 and first frost around October 11.
Your Johnson County Garden Planner — Free
A 22-page printable planner built for Johnson County (Zone 5b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.