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When to Plant Parsley in Imperial County, CA

Imperial County, California Zone 10a May

Imperial County, California gardeners: here's your May plan

Each item below is timed to Imperial County, California's frost dates and soil temperatures. Skip nothing, stress about nothing.

Avg. last frost January 29
Avg. first frost December 20
Soil temp (4") 78°F
Watering Critical
Pest pressure High
Daylight 13.7 hrs
  1. Collect parsley at their peak

    If you can't use it all right away, check the food-preservation section of your planner.

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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.

Imperial County, California is in USDA Zone 10a. The average last spring frost is January 29 and the first fall frost is December 20, giving you a growing season of approximately 325 days.

At an elevation of 181 feet, Imperial County receives approximately 16.8 inches of rainfall annually with predominantly loam soil. Summer highs average 93°F, providing good warmth for Parsley during the growing season. With low rainfall, drip irrigation is essential for growing Parsley successfully. Mulch heavily to conserve soil moisture.

Imperial County, CA (Zone 10a) Year-round
325 days
Last Spring Frost January 29
325 growing days
First Fall Frost December 20
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Imperial County Soil Profile

Soil Type

Loam

Soil pH

5.7-7.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (214 days to spare)
Start indoors: Dec 19 Transplant: Jan 9 🍅 Harvest: Mar 13 – May 15
Recommended (50%) ✓ Fits season (206 days to spare)
Start indoors: Jan 1 Transplant: Jan 22 🍅 Harvest: Mar 26 – May 28
Safe Start (90%) ✓ Fits season (197 days to spare)
Start indoors: Jan 17 Transplant: Feb 7 🍅 Harvest: Apr 11 – Jun 13

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 Imperial County

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

Soil pH

Your soil pH (5.7–7.3) overlaps with Parsley's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.4%). Annual compost additions will help Parsley.

How to Plant Parsley

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

Fall planting: Sow 8 weeks before your first frost date for a fall harvest.

Succession Planting Parsley

6
successive plantings in your 325-day season

Sow every 6.9 weeks. Last sowing by Oct 01 to harvest before frost.

For a dedicated fall crop, sow by Oct 25.

Plant Water Budget

Plant needs
0.6″/week
Rainfall provides
0.2″/week
You supply
0.5″/week
Watering frequency 1-2 times/week
Season total 1,335 gal / 100 sq ft
Drought risk

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

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 2.6" 3" 0" ✅ Rainfall sufficient
Feb 2.6" 3.3" 0" ✅ Rainfall sufficient
Mar 2.6" 3.1" 0" ✅ Rainfall sufficient
Apr 2.6" 1.4" 1.2" 💧 Light watering
May 2.6" 0.4" 2.2" 🚿 Regular watering
Jun 2.6" 0.1" 2.5" 🚿 Regular watering
Jul 2.6" 0" 2.6" 🚿 Regular watering
Aug 2.6" 0" 2.6" 🚿 Regular watering
Sep 2.6" 0.2" 2.4" 🚿 Regular watering
Oct 2.6" 0.6" 2" 🚿 Regular watering
Nov 2.6" 1.5" 1.1" 💧 Light watering
Dec 2.6" 3.3" 0" ✅ Rainfall sufficient

Water needs are for active growing months only (Jan–Dec in Imperial 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 ~1,382 GDD — county provides 6,438 GDD Excellent fit

Parsley Planting Timeline — Imperial County, CA

Parsley Planting Calendar

Activity When Date Range
Start Indoors January 1 Jan 1 – Jan 15
Transplant Outdoors January 22 Jan 22 – Feb 5
Direct Sow January 8 Jan 8 – Jan 29
Harvest March 26 Mar 26 – May 28
Fall Sowing October 25 Oct 25 – Nov 8

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

Month-by-Month Timeline

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

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

0.6"/week · 1-2 times/week

📅 Days to Maturity

60–80 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 10a

📆 Growing Season

325 days in Imperial County

Growing Tips for Parsley in Imperial County

Direct sow Parsley outdoors after January 29 in Imperial 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 Imperial County, CA?

Imperial County is in Zone 10a with an average last frost of January 29. Plan your Parsley planting based on this frost date — see the calendar above for exact timing.

What planting zone is Imperial County, CA?

Imperial County, California is in USDA Hardiness Zone 10a. The average last spring frost is January 29 and first fall frost is December 20.

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Your Imperial County Garden Planner — Free

A 24-page printable planner built for Imperial County (Zone 10a). 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 Imperial County, CA. 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.