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When to Plant Belgian Endive in Clackamas County, OR

Clackamas County, Oregon Zone 9a May

This month in Clackamas County, Oregon

Welcome to May in Zone 9a. These are the moves that will have the biggest impact on your growing season.

Avg. last frost April 14
Avg. first frost October 28
Soil temp (4") 73°F
Watering Moderate
Pest pressure High
Daylight 14.7 hrs
  1. Begin indoor sowing: belgian endive

    Give them 6–8 weeks indoors before the last frost and you'll transplant into warm soil with seedlings that are already leaping.

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Belgian endive is produced by forcing chicory roots in darkness to create tight, pale, torpedo-shaped heads called chicons. They have a mild bitterness and elegant crunch.

Clackamas County, Oregon is in USDA Zone 9a. The average last spring frost is April 14 and the first fall frost is October 28, giving you a growing season of approximately 197 days.

At an elevation of 199 feet, Clackamas County receives approximately 53.1 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85°F, providing good warmth for Belgian Endive during the growing season. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Belgian Endive root diseases.

Clackamas County, OR (Zone 9a) Moderate season
197 days
Last Spring Frost April 14
197 growing days
First Fall Frost October 28
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Clackamas County Soil Profile

Soil Type

Silt Loam

Soil pH

5.7-6.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (29 days to spare)
Start indoors: Mar 7 Transplant: Apr 4 🍅 Harvest: Jul 25 – Sep 19
Recommended (50%) ✓ Fits season (29 days to spare)
Start indoors: Mar 17 Transplant: Apr 14 🍅 Harvest: Aug 4 – Sep 29
Safe Start (90%) ✓ Fits season (33 days to spare)
Start indoors: Apr 9 Transplant: May 7 🍅 Harvest: Aug 27 – Oct 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 Clackamas County

How your county's soil matches Belgian Endive's growing requirements.

Soil pH

Your soil pH (5.7–6.3) is within Belgian Endive's preferred range (5.5–7.0).

Soil Texture

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

Organic Matter

Organic matter is excellent (5.7%) — Belgian Endive will thrive.

How to Plant Belgian Endive

0.5"
Planting Depth
6"
Between Plants
12"
Between Rows

Fall planting: Sow 8 weeks before your first frost date for a fall harvest.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
1.1″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft

Monthly Watering Guide for Belgian Endive

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

Month Belgian Endive Needs Rainfall You Supplement Action
Jan 8.3" 0" ❄️ Dormant
Feb 5.3" 0" ❄️ Dormant
Mar 4.8" 0" ❄️ Dormant
Apr 4.3" 4" 0.3" 💧 Light watering
May 4.3" 3.3" 1" 💧 Light watering
Jun 4.3" 2.1" 2.2" 🚿 Regular watering
Jul 4.3" 0.8" 3.5" 🚿 Regular watering
Aug 4.3" 1" 3.3" 🚿 Regular watering
Sep 4.3" 2.2" 2.1" 💧 Light watering
Oct 4.3" 4.7" 0" ✅ Rainfall sufficient
Nov 8.2" 0" ❄️ Dormant
Dec 8.5" 0" ❄️ Dormant

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

Belgian Endive 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.

Belgian Endive needs ~1,788 GDD — county provides 2,708 GDD Excellent fit

Belgian Endive Planting Timeline — Clackamas County, OR

Belgian Endive Planting Calendar

Activity When Date Range
Start Indoors March 17 Mar 17 – Mar 31
Transplant Outdoors April 14 Apr 14 – Apr 28
Direct Sow March 24 Mar 24 – Apr 14
Harvest August 4 Aug 4 – Sep 29
Fall Sowing September 2 Sep 2 – Sep 16

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

Month-by-Month Timeline

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

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

1"/week · Natural rainfall sufficient

📅 Days to Maturity

110–150 days

🧪 Soil pH

Needs 5.5–7 · Your soil: ideal

🗺️ USDA Zone

Zone 9a

📆 Growing Season

197 days in Clackamas County

Growing Tips for Belgian Endive in Clackamas County

Direct sow Belgian Endive outdoors after April 14 in Clackamas County when soil has warmed and frost danger has passed.

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

General growing tips

Grow chicory roots in the garden during summer, then dig in fall. Trim tops and force roots in moist sand in a dark cellar at 50-60F. Chicons emerge in 3-4 weeks.

Companion Planting

Good Companions

Avoid Planting Near

  • Fennel

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Belgian Endive in Clackamas County, OR?

Clackamas County is in Zone 9a with an average last frost of April 14. Plan your Belgian Endive planting based on this frost date — see the calendar above for exact timing.

What planting zone is Clackamas County, OR?

Clackamas County, Oregon is in USDA Hardiness Zone 9a. The average last spring frost is April 14 and first fall frost is October 28.

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Your Clackamas County Garden Planner — Free

A 24-page printable planner built for Clackamas County (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 Clackamas 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.