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When to Plant Cardoon in Benton County, WA

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.

Benton County, Washington is in USDA Zone 7b. The average last spring frost is April 3 and the first fall frost is October 27, giving you a growing season of approximately 207 days.

At an elevation of 2,633 feet, Benton County receives approximately 22.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 88°F, providing good warmth for Cardoon during the growing season.

Benton County, WA (Zone 7b) Long season
207 days
Last Spring Frost April 3
207 growing days
First Fall Frost October 27

Benton County Soil Profile

Soil Type

Silt Loam

Soil pH

5.5-6.3

Drainage

Well Drained

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 3.2" 0" ❄️ Dormant
Feb 2.6" 0" ❄️ Dormant
Mar 2.1" 0" ❄️ Dormant
Apr 4.3" 1.5" 2.8" 🚿 Regular watering
May 4.3" 1.4" 2.9" 🚿 Regular watering
Jun 4.3" 0.9" 3.4" 🚿 Regular watering
Jul 4.3" 0.4" 3.9" 🚿 Regular watering
Aug 4.3" 0.4" 3.9" 🚿 Regular watering
Sep 4.3" 0.8" 3.5" 🚿 Regular watering
Oct 4.3" 2" 2.3" 🚿 Regular watering
Nov 3.7" 0" ❄️ Dormant
Dec 3.5" 0" ❄️ Dormant

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

Cardoon Planting Timeline — Benton County, WA

Cardoon Planting Calendar

Activity When Date Range
Transplant Outdoors April 17 Apr 17 – May 1
Harvest August 21 Aug 21 – Oct 2

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

Moderate — regular watering

📅 Days to Maturity

120–150 days

🧪 Soil pH

Needs 6–7.5 · Your soil: N/A

🗺️ USDA Zone

Zone 7b

📆 Growing Season

207 days in Benton County

Growing Tips for Benton County

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 Benton County, WA?

Benton County is in Zone 7b with an average last frost of April 3. Plan your Cardoon planting based on this frost date — see the calendar above for exact timing.

What planting zone is Benton County, WA?

Benton County, Washington is in USDA Hardiness Zone 7b. The average last spring frost is April 3 and first fall frost is October 27.

🌱

Your Benton County Garden Planner — Free

A 22-page printable planner built for Benton County (Zone 7b). 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 Benton County, WA. Local conditions may vary. Last updated: June 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.