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When to Plant Marjoram in Imperial County, CA

Imperial County, California Zone 10a May

May in Imperial County, California — your action list

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. Pick marjoram

    Check every 1–2 days. Many of these get tough or go to seed if you wait too long.

Get ahead of June
  • First harvests: marjoram

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Sweet marjoram is a tender perennial herb with a delicate, sweet oregano-like flavor. It is a cornerstone of Mediterranean cooking and pairs well with meats and vegetables.

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 Marjoram during the growing season. With low rainfall, drip irrigation is essential for growing Marjoram 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 (193 days to spare)
Transplant: Jan 23 🍅 Harvest: Mar 27 – Jun 5
Recommended (50%) ✓ Fits season (185 days to spare)
Transplant: Feb 5 🍅 Harvest: Apr 9 – Jun 18
Safe Start (90%) ✓ Fits season (176 days to spare)
Transplant: Feb 21 🍅 Harvest: Apr 25 – Jul 4

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 Marjoram's growing requirements.

Soil pH

Your soil pH (5.7–7.3) overlaps with Marjoram's range (6.5–7.5), though not a perfect match.

Soil Texture

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

Organic Matter

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

How to Plant Marjoram

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

Succession Planting Marjoram

6
successive plantings in your 325-day season

Sow every 6.9 weeks. Last sowing by Sep 21 to harvest before frost.

Plant Water Budget

Plant needs
0.3″/week
Rainfall provides
0.2″/week
You supply
0.1″/week
Watering frequency Only during dry spells
Season total 291 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Marjoram

Marjoram needs approximately 0.3 inches of water per week (1.3" per month). Here's how your county's rainfall compares month by month.

Month Marjoram Needs Rainfall You Supplement Action
Jan 1.3" 3" 0" ✅ Rainfall sufficient
Feb 1.3" 3.3" 0" ✅ Rainfall sufficient
Mar 1.3" 3.1" 0" ✅ Rainfall sufficient
Apr 1.3" 1.4" 0" ✅ Rainfall sufficient
May 1.3" 0.4" 0.9" 🚿 Regular watering
Jun 1.3" 0.1" 1.2" 🚿 Regular watering
Jul 1.3" 0" 1.3" 🚿 Regular watering
Aug 1.3" 0" 1.3" 🚿 Regular watering
Sep 1.3" 0.2" 1.1" 🚿 Regular watering
Oct 1.3" 0.6" 0.7" 🚿 Regular watering
Nov 1.3" 1.5" 0" ✅ Rainfall sufficient
Dec 1.3" 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.

Marjoram 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.

Marjoram needs ~1,481 GDD — county provides 6,438 GDD Excellent fit

Marjoram Planting Timeline — Imperial County, CA

Marjoram Planting Calendar

Activity When Date Range
Transplant Outdoors February 5 Feb 5 – Feb 19
Harvest April 9 Apr 9 – Jun 18

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

Month-by-Month Timeline

MonthActivities
January
February Transplant Outdoors
March
April Harvest
May Harvest
June Harvest
July
August
September
October
November
December
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Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.3"/week · Only during dry spells

📅 Days to Maturity

60–90 days

🧪 Soil pH

Needs 6.5–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 10a

📆 Growing Season

325 days in Imperial County

Growing Tips for Marjoram in Imperial County

Direct sow Marjoram outdoors after January 29 in Imperial County when soil has warmed and frost danger has passed.

General growing tips

Start seeds indoors 6-8 weeks before last frost. Harvest stems just as flower buds appear for peak flavor. In cold climates, grow as an annual or bring containers indoors.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Marjoram in Imperial County, CA?

Imperial County is in Zone 10a with an average last frost of January 29. Plan your Marjoram 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.