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When to Plant Cardoon in Alameda County, CA

Alameda County, California Zone 10a May

Your May game plan for Alameda County, California

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

Avg. last frost January 18
Avg. first frost December 12
Soil temp (4") 76°F
Watering Critical
Pest pressure High
Daylight 14 hrs
June will be here before you know it — start on
  • First harvests: cardoon

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Cardoon is a large thistle relative of the artichoke, grown for its edible leaf stalks. It has dramatic silvery foliage and makes a striking ornamental as well.

Alameda County, California is in USDA Zone 10a. The average last spring frost is January 18 and the first fall frost is December 12, giving you a growing season of approximately 328 days.

At an elevation of 379 feet, Alameda County receives approximately 16.4 inches of rainfall annually with predominantly loam soil. Summer highs average 97°F, so Cardoon may need afternoon shade and extra watering during peak heat. With low rainfall, drip irrigation is essential for growing Cardoon successfully. Mulch heavily to conserve soil moisture.

Alameda County, CA (Zone 10a) Year-round
328 days
Last Spring Frost January 18
328 growing days
First Fall Frost December 12
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Alameda County Soil Profile

Soil Type

Loam

Soil pH

6.3-7.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (143 days to spare)
Transplant: Jan 28 🍅 Harvest: Jun 3 – Jul 15
Recommended (50%) ✓ Fits season (146 days to spare)
Transplant: Feb 1 🍅 Harvest: Jun 7 – Jul 19
Safe Start (90%) ✓ Fits season (93 days to spare)
Transplant: Apr 7 🍅 Harvest: Aug 11 – Sep 22

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 Alameda County

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

Soil pH

Your soil pH (6.3–7.7) overlaps with Cardoon's range (6.0–7.5), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is moderate (3.0%). Annual compost additions will help Cardoon.

How to Plant Cardoon

1"
Planting Depth
30"
Between Plants
42"
Between Rows

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.2″/week
You supply
1.0″/week
Watering frequency 2-3 times/week
Season total 2,778 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Cardoon

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

Month Cardoon Needs Rainfall You Supplement Action
Jan 4.3" 3" 1.3" 💧 Light watering
Feb 4.3" 3.6" 0.7" 💧 Light watering
Mar 4.3" 2.6" 1.7" 💧 Light watering
Apr 4.3" 1.2" 3.1" 🚿 Regular watering
May 4.3" 0.4" 3.9" 🚿 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" 0.2" 4.1" 🚿 Regular watering
Oct 4.3" 0.6" 3.7" 🚿 Regular watering
Nov 4.3" 1.5" 2.8" 🚿 Regular watering
Dec 4.3" 3.1" 1.2" 💧 Light watering

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

Cardoon 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.

Cardoon needs ~3,071 GDD — county provides 7,484 GDD Excellent fit

Cardoon Planting Timeline — Alameda County, CA

Cardoon Planting Calendar

Activity When Date Range
Transplant Outdoors February 1 Feb 1 – Feb 15
Harvest June 7 Jun 7 – Jul 19

Plant 1" deep · 30" apart · Rows 42" apart

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · 2-3 times/week

📅 Days to Maturity

120–150 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 10a

📆 Growing Season

328 days in Alameda County

Growing Tips for Cardoon in Alameda County

Direct sow Cardoon outdoors after January 18 in Alameda County when soil has warmed and frost danger has passed.

With summer highs reaching 97°F in Alameda County, provide afternoon shade for Cardoon and water deeply in the morning.

Common pests for Cardoon in this region include aphids and slugs. Use row covers early in the season and inspect plants weekly.

Alameda County receives only 16" of rain annually. Cardoon needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

General growing tips

Blanch stalks by wrapping with cardboard or tying leaves together 3-4 weeks before harvest. Provide deep, rich soil and consistent moisture. Protect from hard frost.

Companion Planting

Good Companions

Avoid Planting Near

  • Fennel

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Cardoon in Alameda County, CA?

Alameda County is in Zone 10a with an average last frost of January 18. Plan your Cardoon planting based on this frost date — see the calendar above for exact timing.

What planting zone is Alameda County, CA?

Alameda County, California is in USDA Hardiness Zone 10a. The average last spring frost is January 18 and first fall frost is December 12.

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Your Alameda County Garden Planner — Free

A 24-page printable planner built for Alameda 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 Alameda 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.