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When to Plant Arugula in Monterey County, CA

Monterey County, California Zone 9b April

Monterey County, California gardeners: here's your April plan

April rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Monterey County, California.

Avg. last frost March 13
Avg. first frost November 17
Soil temp (4") 67°F
Watering Critical
Pest pressure High
Daylight 12.9 hrs
  1. Start arugula indoors

    Your window is short. These crops want several weeks of indoor growth before they go outside.

  2. It's harvest week for arugula

    Don't tug. Use scissors or pruners for clean cuts — torn stems invite disease.

Before May arrives, get these ready
  • First harvests: arugula

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Arugula is a fast-growing cool-season green with a peppery, nutty flavor. It is excellent in salads and can be harvested as baby greens or mature leaves.

Monterey County, California is in USDA Zone 9b. The average last spring frost is March 13 and the first fall frost is November 17, giving you a growing season of approximately 249 days.

At an elevation of 260 feet, Monterey County receives approximately 12.5 inches of rainfall annually with predominantly loam soil. Summer highs average 93°F, providing good warmth for Arugula during the growing season. With low rainfall, drip irrigation is essential for growing Arugula successfully. Mulch heavily to conserve soil moisture.

Monterey County, CA (Zone 9b) Long season
249 days
Last Spring Frost March 13
249 growing days
First Fall Frost November 17

Monterey County Soil Profile

Soil Type

Loam

Soil pH

6.7-7.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (150 days to spare)
Start indoors: Jan 30 Transplant: Feb 27 🍅 Harvest: Apr 3 – Jun 5
Recommended (50%) ✓ Fits season (151 days to spare)
Start indoors: Feb 13 Transplant: Mar 13 🍅 Harvest: Apr 17 – Jun 19
Safe Start (90%) ✓ Fits season (116 days to spare)
Start indoors: Apr 19 Transplant: May 17 🍅 Harvest: Jun 21 – Aug 23

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 Monterey County

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

Soil pH

Your soil pH (6.7–7.2) overlaps with Arugula's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.7%). Annual compost additions will help Arugula.

How to Plant Arugula

0.5"
Planting Depth
6"
Between Plants
12"
Between Rows

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

Succession Planting Arugula

10
successive plantings in your 249-day season

Sow every 3.4 weeks. Last sowing by Sep 28 to harvest before frost.

For a dedicated fall crop, sow by Sep 22.

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 1,035 gal / 100 sq ft
Drought risk

Water stress score is 8/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Arugula

Arugula 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 Arugula Needs Rainfall You Supplement Action
Jan 2.7" 0" ❄️ Dormant
Feb 2.6" 0" ❄️ Dormant
Mar 2.6" 2.1" 0.5" 💧 Light watering
Apr 2.6" 1" 1.6" 🚿 Regular watering
May 2.6" 0.3" 2.3" 🚿 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" 0.1" 2.5" 🚿 Regular watering
Oct 2.6" 0.5" 2.1" 🚿 Regular watering
Nov 2.6" 1.2" 1.4" 🚿 Regular watering
Dec 1.9" 0" ❄️ Dormant

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

Arugula 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.

Arugula needs ~790 GDD — county provides 4,917 GDD Excellent fit

Arugula Planting Timeline — Monterey County, CA

Arugula Planting Calendar

Activity When Date Range
Start Indoors February 13 Feb 13 – Feb 27
Transplant Outdoors March 13 Mar 13 – Mar 27
Direct Sow February 20 Feb 20 – Mar 13
Harvest April 17 Apr 17 – Jun 19
Fall Sowing September 22 Sep 22 – Oct 6

Plant 0.5" deep · 6" apart · Rows 12" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

0.6"/week · 1-2 times/week

📅 Days to Maturity

30–50 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 9b

📆 Growing Season

249 days in Monterey County

Growing Tips for Arugula in Monterey County

Direct sow Arugula outdoors after March 13 in Monterey County when soil has warmed and frost danger has passed.

Summer highs in Monterey County reach 93°F — grow Arugula as a spring or fall crop. Use shade cloth if planting in summer.

Your generous 249.0-day season in Monterey County allows multiple plantings of Arugula. Sow every 15.0 days for continuous harvest.

Common pests for Arugula in this region include cabbage worm and flea beetles. Use row covers early in the season and inspect plants weekly.

General growing tips

Sow seeds directly every 2-3 weeks for continuous harvest. Provide afternoon shade in warm weather to prevent bolting. Harvest outer leaves first to extend production.

Companion Planting

Good Companions

Avoid Planting Near

  • Strawberries

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Arugula in Monterey County, CA?

Monterey County is in Zone 9b with an average last frost of March 13. Plan your Arugula planting based on this frost date — see the calendar above for exact timing.

What planting zone is Monterey County, CA?

Monterey County, California is in USDA Hardiness Zone 9b. The average last spring frost is March 13 and first fall frost is November 17.

🌱

Your Monterey County Garden Planner — Free

A 24-page printable planner built for Monterey County (Zone 9b). 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 Monterey County, CA. 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.