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When to Plant Cardoon in Linn County, OR

Linn County, Oregon Zone 8b May

This month in Linn County, Oregon

May is a pivotal month for Linn County, Oregon gardens. Focus on these tasks first and you'll set up the rest of the season for success.

Avg. last frost April 22
Avg. first frost October 25
Soil temp (4") 69°F
Watering High
Pest pressure High
Daylight 14.6 hrs
  1. Move cardoon from tray to bed

    Water the tray well an hour before you transplant. Roots slide out cleanly and settle in faster.

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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.

Linn County, Oregon is in USDA Zone 8b. The average last spring frost is April 22 and the first fall frost is October 25, giving you a growing season of approximately 186 days.

At an elevation of 259 feet, Linn County receives approximately 37.2 inches of rainfall annually with predominantly silt loam soil. Summer highs average 81°F, so choose short-season varieties of Cardoon to ensure they mature before fall.

Linn County, OR (Zone 8b) Moderate season
186 days
Last Spring Frost April 22
186 growing days
First Fall Frost October 25

Linn County Soil Profile

Soil Type

Silt Loam

Soil pH

5.6-6.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (3 days to spare)
Transplant: Apr 29 🍅 Harvest: Sep 2 – Oct 14
Recommended (50%) ✓ Fits season (4 days to spare)
Transplant: May 6 🍅 Harvest: Sep 9 – Oct 21
Safe Start (90%) ✓ Fits season (7 days to spare)
Transplant: May 29 🍅 Harvest: Oct 2 – Nov 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 Linn County

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

Soil pH

Your soil pH (5.6–6.3) is more acidic than Cardoon prefers (6.0–7.5). Add garden lime to raise pH.

Soil Texture

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

Organic Matter

Organic matter is excellent (5.4%) — Cardoon will thrive.

How to Plant Cardoon

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

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.8″/week
You supply
0.2″/week
Watering frequency Only during dry spells
Season total 265 gal / 100 sq ft

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 5.8" 0" ❄️ Dormant
Feb 3.8" 0" ❄️ Dormant
Mar 4.2" 0" ❄️ Dormant
Apr 4.3" 2.7" 1.6" 💧 Light watering
May 4.3" 2" 2.3" 🚿 Regular watering
Jun 4.3" 1.4" 2.9" 🚿 Regular watering
Jul 4.3" 0.6" 3.7" 🚿 Regular watering
Aug 4.3" 0.6" 3.7" 🚿 Regular watering
Sep 4.3" 1.4" 2.9" 🚿 Regular watering
Oct 4.3" 3.5" 0.8" 💧 Light watering
Nov 5.4" 0" ❄️ Dormant
Dec 5.9" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Linn 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 ~1,451 GDD — county provides 1,999 GDD Excellent fit

Cardoon Planting Timeline — Linn County, OR

Cardoon Planting Calendar

Activity When Date Range
Transplant Outdoors May 6 May 6 – May 20
Harvest September 9 Sep 9 – Oct 21

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Only during dry spells

📅 Days to Maturity

120–150 days

🧪 Soil pH

Needs 6–7.5 · Your soil: too_acidic

🗺️ USDA Zone

Zone 8b

📆 Growing Season

186 days in Linn County

Growing Tips for Cardoon in Linn County

Direct sow Cardoon outdoors after April 22 in Linn County when soil has warmed and frost danger has passed.

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

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 Linn County, OR?

Linn County is in Zone 8b with an average last frost of April 22. Plan your Cardoon planting based on this frost date — see the calendar above for exact timing.

What planting zone is Linn County, OR?

Linn County, Oregon is in USDA Hardiness Zone 8b. The average last spring frost is April 22 and first fall frost is October 25.

🌱

Your Linn County Garden Planner — Free

A 24-page printable planner built for Linn 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.

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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 Linn County, OR. 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.