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When to Plant Arugula in Trinity County, CA

Trinity County, California Zone 8b May

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

A quick May briefing for Trinity County, California gardeners — what's urgent, what's next, and what can wait.

Avg. last frost April 19
Avg. first frost October 25
Soil temp (4") 69°F
Watering Critical
Pest pressure Moderate
Daylight 14.3 hrs
  1. Sow arugula in trays indoors

    These need a head start before your last frost (April 19). Sow into cells now so you're ready to transplant in a few weeks.

  2. Bring in the arugula

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

To set up a strong June, finish these tasks
  • 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.

Trinity County, California is in USDA Zone 8b. The average last spring frost is April 19 and the first fall frost is October 25, giving you a growing season of approximately 189 days.

At an elevation of 61 feet, Trinity County receives approximately 30.9 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 79°F, so choose short-season varieties of Arugula to ensure they mature before fall. Sandy soil warms quickly in spring — great for early planting — but Arugula will need more frequent watering and organic matter to retain nutrients.

Trinity County, CA (Zone 8b) Moderate season
189 days
Last Spring Frost April 19
189 growing days
First Fall Frost October 25

Trinity County Soil Profile

Soil Type

Sandy Loam

Soil pH

6-7.1

Drainage

Well Drained

Monthly Watering Guide for Arugula

Arugula needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Arugula Needs Rainfall You Supplement Action
Jan 6.2" 0" ❄️ Dormant
Feb 6.6" 0" ❄️ Dormant
Mar 5" 0" ❄️ Dormant
Apr 4.3" 2.7" 1.6" 💧 Light watering
May 4.3" 0.9" 3.4" 🚿 Regular watering
Jun 4.3" 0.1" 4.2" 🚿 Regular watering
Jul 4.3" 0" 4.3" 🚿 Regular watering
Aug 4.3" 0" 4.3" 🚿 Regular watering
Sep 4.3" 0.3" 4" 🚿 Regular watering
Oct 4.3" 1.2" 3.1" 🚿 Regular watering
Nov 2.9" 0" ❄️ Dormant
Dec 4.9" 0" ❄️ Dormant

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

Arugula Planting Timeline — Trinity County, CA

Arugula Planting Calendar

Activity When Date Range
Start Indoors March 15 Mar 15 – Mar 29
Transplant Outdoors April 19 Apr 19 – May 3
Direct Sow April 5 Apr 5 – Apr 26
Harvest May 24 May 24 – Jul 26
Fall Sowing August 16 Aug 16 – Aug 30

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

Moderate — regular watering

📅 Days to Maturity

30–50 days

🧪 Soil pH

Needs 6–7 · Your soil: N/A

🗺️ USDA Zone

Zone 8b

📆 Growing Season

189 days in Trinity County

Growing Tips for Trinity County

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 Trinity County, CA?

Trinity County is in Zone 8b with an average last frost of April 19. Plan your Arugula planting based on this frost date — see the calendar above for exact timing.

What planting zone is Trinity County, CA?

Trinity County, California is in USDA Hardiness Zone 8b. The average last spring frost is April 19 and first fall frost is October 25.

🌱

Your Trinity County Garden Planner — Free

A 24-page printable planner built for Trinity County (Zone 8b). 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 Trinity 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.