Blog

When to Plant Parsley in Plymouth County, IA

Plymouth County, Iowa Zone 4b April

Your April planting checklist for Plymouth County, Iowa

Your Plymouth County, Iowa garden is entering a new phase. Here's what's on the schedule for April and why each task matters now.

Avg. last frost April 30
Avg. first frost October 6
Soil temp (4") 41°F
Watering Low
Pest pressure Low
Daylight 13.2 hrs
  1. Get parsley in the ground

    Pick a cloudy afternoon or evening to plant. Less transplant shock, and your seedlings will barely blink.

  2. Scatter parsley into prepared beds

    Sow every 2 weeks for a continuous harvest. A single big planting means a single big glut.

Instant PDF download. No spam, unsubscribe any time.

Parsley is a biennial herb available in flat-leaf (Italian) and curly varieties. It is a nutritional powerhouse rich in vitamins C and K and adds fresh flavor to countless dishes.

Plymouth County, Iowa is in USDA Zone 4b. The average last spring frost is April 30 and the first fall frost is October 6, giving you a growing season of approximately 159 days.

At an elevation of 1,392 feet, Plymouth County receives approximately 38 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83°F, so choose short-season varieties of Parsley to ensure they mature before fall.

Plymouth County, IA (Zone 4b) Moderate season
159 days
Last Spring Frost April 30
159 growing days
First Fall Frost October 6
Share this guide:

Plymouth 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 (45 days to spare)
Start indoors: Mar 10 Transplant: Apr 14 🍅 Harvest: Jun 16 – Aug 18
Recommended (50%) ✓ Fits season (40 days to spare)
Start indoors: Mar 19 Transplant: Apr 23 🍅 Harvest: Jun 25 – Aug 27
Safe Start (90%) ✓ Fits season (36 days to spare)
Start indoors: Apr 2 Transplant: May 7 🍅 Harvest: Jul 9 – Sep 10

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 Plymouth County

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

Soil pH

Your soil pH (6.0–7.2) overlaps with Parsley's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is excellent (4.7%) — Parsley will thrive.

How to Plant Parsley

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

Fall planting: Sow 12 weeks before your first frost date for a fall harvest.

Succession Planting Parsley

3
successive plantings in your 159-day season

Sow every 6.9 weeks. Last sowing by Jul 18 to harvest before frost.

For a dedicated fall crop, sow by Jul 14.

Plant Water Budget

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

Monthly Watering Guide for Parsley

Parsley needs approximately 0.6 inches of water per week (2.6" per month). Here's how your county's rainfall compares month by month.

Month Parsley Needs Rainfall You Supplement Action
Jan 1.6" 0" ❄️ Dormant
Feb 1.4" 0" ❄️ Dormant
Mar 2.6" 0" ❄️ Dormant
Apr 2.6" 3.9" 0" ✅ Rainfall sufficient
May 2.6" 4.8" 0" ✅ Rainfall sufficient
Jun 2.6" 4.2" 0" ✅ Rainfall sufficient
Jul 2.6" 4.4" 0" ✅ Rainfall sufficient
Aug 2.6" 4.3" 0" ✅ Rainfall sufficient
Sep 2.6" 3.4" 0" ✅ Rainfall sufficient
Oct 2.6" 2.7" 0" ✅ Rainfall sufficient
Nov 2.8" 0" ❄️ Dormant
Dec 1.9" 0" ❄️ Dormant

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

Parsley 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.

Parsley needs ~858 GDD — county provides 1,947 GDD Excellent fit

Parsley Planting Timeline — Plymouth County, IA

Parsley Planting Calendar

Activity When Date Range
Start Indoors March 19 Mar 19 – Apr 2
Transplant Outdoors April 23 Apr 23 – May 7
Direct Sow April 23 Apr 23 – May 14
Harvest June 25 Jun 25 – Aug 27
Fall Sowing July 14 Jul 14 – Jul 28

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 Transplant Outdoors Direct Sow
June Harvest
July Fall Sowing Harvest
August Harvest
September
October
November
December
Share this guide:

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

0.6"/week · Natural rainfall sufficient

📅 Days to Maturity

60–80 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 4b

📆 Growing Season

159 days in Plymouth County

Growing Tips for Parsley in Plymouth County

Direct sow Parsley outdoors after April 30 in Plymouth County when soil has warmed and frost danger has passed.

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

General growing tips

Start seeds indoors 6-8 weeks before last frost. Soak seeds overnight as germination is slow. Harvest outer stems first to keep plants productive. Parsley attracts swallowtail butterflies.

Companion Planting

Good Companions

Avoid Planting Near

  • Mint
  • Lettuce

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Parsley in Plymouth County, IA?

Plymouth County is in Zone 4b with an average last frost of April 30. Plan your Parsley planting based on this frost date — see the calendar above for exact timing.

What planting zone is Plymouth County, IA?

Plymouth County, Iowa is in USDA Hardiness Zone 4b. The average last spring frost is April 30 and first fall frost is October 6.

🌱

Your Plymouth County Garden Planner — Free

A 24-page printable planner built for Plymouth County (Zone 4b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

Instant PDF download. No spam, unsubscribe any time.

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

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.