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When to Plant Chervil in Keokuk County, IA

Keokuk County, Iowa Zone 5b May

What to do in May

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

Avg. last frost April 23
Avg. first frost October 12
Soil temp (4") 59°F
Watering Low
Pest pressure Low
Daylight 14.3 hrs
  1. Begin indoor sowing: chervil

    Give them 6–8 weeks indoors before the last frost and you'll transplant into warm soil with seedlings that are already leaping.

  2. It's harvest week for chervil

    The more you pick, the more the plant produces. Letting fruit overripen tells the plant it's time to stop.

A few tasks this May that'll pay off in June
  • First harvests: chervil

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Chervil is a delicate herb with a subtle anise-parsley flavor, essential in French cuisine as part of fines herbes. It prefers cool conditions and partial shade.

Keokuk County, Iowa is in USDA Zone 5b. The average last spring frost is April 23 and the first fall frost is October 12, giving you a growing season of approximately 172 days.

At an elevation of 654 feet, Keokuk County receives approximately 41.7 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83°F, so choose short-season varieties of Chervil to ensure they mature before fall.

Keokuk County, IA (Zone 5b) Moderate season
172 days
Last Spring Frost April 23
172 growing days
First Fall Frost October 12
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Keokuk County Soil Profile

Soil Type

Silt Loam

Soil pH

6-6.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (73 days to spare)
Start indoors: Mar 13 Transplant: Apr 10 🍅 Harvest: May 22 – Jul 24
Recommended (50%) ✓ Fits season (74 days to spare)
Start indoors: Mar 19 Transplant: Apr 16 🍅 Harvest: May 28 – Jul 30
Safe Start (90%) ✓ Fits season (71 days to spare)
Start indoors: Apr 3 Transplant: May 1 🍅 Harvest: Jun 12 – Aug 14

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 Keokuk County

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

Soil pH

Your soil pH (6.0–6.7) is within Chervil's preferred range (6.0–7.0).

Soil Texture

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

Organic Matter

Organic matter is excellent (5.0%) — Chervil will thrive.

How to Plant Chervil

0.5"
Planting Depth
8"
Between Plants
12"
Between Rows

Fall planting: Sow 10 weeks before your first frost date for a fall harvest.

Succession Planting Chervil

5
successive plantings in your 172-day season

Sow every 4.6 weeks. Last sowing by Aug 13 to harvest before frost.

For a dedicated fall crop, sow by Aug 03.

Plant Water Budget

Plant needs
0.5″/week
Rainfall provides
1.0″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Chervil

Chervil 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 Chervil Needs Rainfall You Supplement Action
Jan 1.6" 0" ❄️ Dormant
Feb 1.7" 0" ❄️ Dormant
Mar 2.6" 0" ❄️ Dormant
Apr 2.2" 4.3" 0" ✅ Rainfall sufficient
May 2.2" 4.9" 0" ✅ Rainfall sufficient
Jun 2.2" 5.7" 0" ✅ Rainfall sufficient
Jul 2.2" 4.2" 0" ✅ Rainfall sufficient
Aug 2.2" 4.4" 0" ✅ Rainfall sufficient
Sep 2.2" 3.8" 0" ✅ Rainfall sufficient
Oct 2.2" 3.4" 0" ✅ Rainfall sufficient
Nov 2.7" 0" ❄️ Dormant
Dec 2.2" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Keokuk County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Chervil 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.

Chervil needs ~612 GDD — county provides 2,107 GDD Excellent fit

Chervil Planting Timeline — Keokuk County, IA

Chervil Planting Calendar

Activity When Date Range
Start Indoors March 19 Mar 19 – Apr 2
Transplant Outdoors April 16 Apr 16 – Apr 30
Direct Sow April 9 Apr 9 – Apr 30
Harvest May 28 May 28 – Jul 30
Fall Sowing August 3 Aug 3 – Aug 17

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

Month-by-Month Timeline

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

🗺️ USDA Zone

Zone 5b

📆 Growing Season

172 days in Keokuk County

Growing Tips for Chervil in Keokuk County

Direct sow Chervil outdoors after April 23 in Keokuk County when soil has warmed and frost danger has passed.

Your generous 172.0-day season in Keokuk County allows multiple plantings of Chervil. Sow every 20.0 days for continuous harvest.

Common pests for Chervil in this region include carrot rust fly and parsleyworm. Use row covers early in the season and inspect plants weekly.

General growing tips

Direct sow in early spring or fall as chervil bolts in heat. Provide shade and cool conditions. Harvest outer leaves as needed; use fresh as it loses flavor when dried.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Chervil in Keokuk County, IA?

Keokuk County is in Zone 5b with an average last frost of April 23. Plan your Chervil planting based on this frost date — see the calendar above for exact timing.

What planting zone is Keokuk County, IA?

Keokuk County, Iowa is in USDA Hardiness Zone 5b. The average last spring frost is April 23 and first fall frost is October 12.

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Your Keokuk County Garden Planner — Free

A 24-page printable planner built for Keokuk 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.

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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 Keokuk County, IA. 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.