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When to plant Oregano in Williamson County, IL

Williamson County's short 193-day growing season means one Oregano planting between April 17 and May 1. No fall crop in Zone 7a.

When to Plant Oregano in Williamson County, IL

Oregano

Oregano is a robust perennial herb essential to Italian and Greek cuisine. Its pungent, savory leaves intensify in flavor when dried.

Williamson County, Illinois is in USDA Zone 7a. The average last spring frost is April 10 and the first fall frost is October 20, giving you a growing season of approximately 193 days.

At an elevation of 1,253 feet, Williamson County receives approximately 38.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 91°F, providing good warmth for Oregano during the growing season.

Williamson County, IL (Zone 7a) Moderate season
193 days
Last Spring Frost April 10
193 growing days
First Fall Frost October 20

Williamson County Soil Profile

Soil Type

Silt Loam

Soil pH

6.2-7.2

Drainage

Well Drained

Monthly Watering Guide for Oregano

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

Month Oregano Needs Rainfall You Supplement Action
Jan 1.7" 0" ❄️ Dormant
Feb 1.8" 0" ❄️ Dormant
Mar 2.2" 0" ❄️ Dormant
Apr 4.3" 4" 0.3" 💧 Light watering
May 4.3" 4.9" 0" ✅ Rainfall sufficient
Jun 4.3" 4.8" 0" ✅ Rainfall sufficient
Jul 4.3" 4.3" 0" ✅ Rainfall sufficient
Aug 4.3" 3.7" 0.6" 💧 Light watering
Sep 4.3" 3.2" 1.1" 💧 Light watering
Oct 4.3" 2.9" 1.4" 💧 Light watering
Nov 2.4" 0" ❄️ Dormant
Dec 2.4" 0" ❄️ Dormant

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

Oregano Planting Timeline — Williamson County, IL

Oregano Planting Calendar

Activity When Date Range
Transplant Outdoors April 17 Apr 17 – May 1
Harvest June 19 Jun 19 – Aug 28

Plant 0.5" deep · 8" apart · Rows 12" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

Low — drought tolerant

📅 Days to Maturity

60–90 days

🧪 Soil pH

Needs 6–8 · Your soil: N/A

🗺️ USDA Zone

Zone 7a

📆 Growing Season

193 days in Williamson County

Growing Tips for Williamson County

Start from seed, cuttings, or divisions. Harvest just before flowering for strongest flavor. Cut plants back to a few inches in spring to encourage vigorous new growth.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Oregano in Williamson County, IL?

Williamson County is in Zone 7a with an average last frost of April 10. Plan your Oregano planting based on this frost date — see the calendar above for exact timing.

What planting zone is Williamson County, IL?

Williamson County, Illinois is in USDA Hardiness Zone 7a. The average last spring frost is April 10 and first fall frost is October 20.

When should I plant Oregano in Williamson County, IL?

In Williamson County, IL, plant Oregano after the last frost (around April 10) and before the first frost (around October 20). Best results when soil holds above 50°F.

What growing zone is Williamson County, IL for Oregano?

Williamson County sits in USDA Zone 7a. Oregano grows reliably in zones 4a through 10b, so it's a good fit here.

Can Oregano grow in Williamson County's climate?

Yes — Oregano grows well in Williamson County's temperate climate. Williamson County averages a 193-day frost-free season, with last frost around April 10 and first frost around October 20.

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Your Williamson County Garden Planner — Free

A 22-page printable planner built for Williamson County (Zone 7a). 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 Williamson County, IL. Local conditions may vary. Last updated: July 2026.

Sources & credits

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