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When to Plant Cardoon in Washington Parish, LA

Washington Parish, Louisiana Zone 9a May

Your May gardening checklist

We've pulled the most time-sensitive tasks for Washington Parish, Louisiana this May and put them front and centre. Tackle them in order.

Avg. last frost March 11
Avg. first frost November 22
Soil temp (4") 74°F
Watering Low
Pest pressure High
Daylight 13.6 hrs

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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.

Washington Parish, Louisiana is in USDA Zone 9a. The average last spring frost is March 11 and the first fall frost is November 22, giving you a growing season of approximately 256 days.

At an elevation of 439 feet, Washington Parish receives approximately 56.4 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 93°F, providing good warmth for Cardoon during the growing season. Sandy soil warms quickly in spring — great for early planting — but Cardoon will need more frequent watering and organic matter to retain nutrients. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Cardoon root diseases.

Washington Parish, LA (Zone 9a) Long season
256 days
Last Spring Frost March 11
256 growing days
First Fall Frost November 22
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Washington Parish Soil Profile

Soil Type

Sandy Loam

Soil pH

5.1-6.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (76 days to spare)
Transplant: Mar 16 🍅 Harvest: Jul 20 – Aug 31
Recommended (50%) ✓ Fits season (74 days to spare)
Transplant: Mar 25 🍅 Harvest: Jul 29 – Sep 9
Safe Start (90%) ✓ Fits season (75 days to spare)
Transplant: Apr 13 🍅 Harvest: Aug 17 – Sep 28

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 Washington Parish

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

Soil pH

Your soil pH (5.1–6.3) is more acidic than Cardoon prefers (6.0–7.5). Add garden lime to raise pH.

Soil Texture

Sandy soil in Washington Parish warms quickly in spring but drains fast. Cardoon will need more frequent watering and regular compost additions to retain nutrients.

Drainage

Drainage is adequate for Cardoon.

Organic Matter

Organic matter is low (1.9%). Add 2-3 inches of compost before planting Cardoon.

How to Plant Cardoon

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

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.9″/week
Watering frequency Natural rainfall sufficient
Season total 0 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 4.9" 0" ❄️ Dormant
Feb 5" 0" ❄️ Dormant
Mar 4.3" 5.7" 0" ✅ Rainfall sufficient
Apr 4.3" 4.2" 0.1" 💧 Light watering
May 4.3" 4.7" 0" ✅ Rainfall sufficient
Jun 4.3" 4.6" 0" ✅ Rainfall sufficient
Jul 4.3" 5.4" 0" ✅ Rainfall sufficient
Aug 4.3" 5.2" 0" ✅ Rainfall sufficient
Sep 4.3" 3.8" 0.5" 💧 Light watering
Oct 4.3" 4.1" 0.2" 💧 Light watering
Nov 4.3" 4.1" 0.2" 💧 Light watering
Dec 4.7" 0" ❄️ Dormant

Water needs are for active growing months only (Mar–Nov in Washington Parish). 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 ~2,666 GDD — county provides 5,056 GDD Excellent fit

Cardoon Planting Timeline — Washington Parish, LA

Cardoon Planting Calendar

Activity When Date Range
Transplant Outdoors March 25 Mar 25 – Apr 8
Harvest July 29 Jul 29 – Sep 9

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

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Natural rainfall sufficient

📅 Days to Maturity

120–150 days

🧪 Soil pH

Needs 6–7.5 · Your soil: too_acidic

🗺️ USDA Zone

Zone 9a

📆 Growing Season

256 days in Washington Parish

Growing Tips for Cardoon in Washington Parish

Direct sow Cardoon outdoors after March 11 in Washington Parish when soil has warmed and frost danger has passed.

Sandy soil in Washington Parish dries quickly — mulch Cardoon with 2-3 inches of straw and water deeply 2-3 times per week rather than lightly every day.

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 Washington Parish, LA?

Washington Parish is in Zone 9a with an average last frost of March 11. Plan your Cardoon planting based on this frost date — see the calendar above for exact timing.

What planting zone is Washington Parish, LA?

Washington Parish, Louisiana is in USDA Hardiness Zone 9a. The average last spring frost is March 11 and first fall frost is November 22.

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Your Washington Parish Garden Planner — Free

A 24-page printable planner built for Washington Parish (Zone 9a). 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 Washington Parish, LA. Local conditions may vary. Last updated: May 2026.

Sources & credits

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