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When to Plant Oregano in Cass County, MO

Cass County, Missouri Zone 6b May

What to do in May

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

Avg. last frost April 14
Avg. first frost October 22
Soil temp (4") 64°F
Watering Low
Pest pressure Low
Daylight 14.1 hrs
Looking ahead to June
  • First harvests: oregano

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

Cass County, Missouri is in USDA Zone 6b. The average last spring frost is April 14 and the first fall frost is October 22, giving you a growing season of approximately 191 days.

At an elevation of 910 feet, Cass County receives approximately 37 inches of rainfall annually with predominantly silt loam soil. Summer highs average 87°F, providing good warmth for Oregano during the growing season.

Cass County, MO (Zone 6b) Moderate season
191 days
Last Spring Frost April 14
191 growing days
First Fall Frost October 22

Cass County Soil Profile

Soil Type

Silt Loam

Soil pH

5.7-6.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (51 days to spare)
Transplant: Apr 14 🍅 Harvest: Jun 16 – Aug 25
Recommended (50%) ✓ Fits season (51 days to spare)
Transplant: Apr 21 🍅 Harvest: Jun 23 – Sep 1
Safe Start (90%) ✓ Fits season (48 days to spare)
Transplant: May 8 🍅 Harvest: Jul 10 – Sep 18

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 Cass County

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

Soil pH

Your soil pH (5.7–6.8) overlaps with Oregano's range (6.0–8.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.9%). Annual compost additions will help Oregano.

How to Plant Oregano

0.5"
Planting Depth
8"
Between Plants
12"
Between Rows

Succession Planting Oregano

3
successive plantings in your 191-day season

Sow every 6.9 weeks. Last sowing by Jul 24 to harvest before frost.

Plant Water Budget

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

Monthly Watering Guide for Oregano

Oregano needs approximately 0.3 inches of water per week (1.3" per month). Here's how your county's rainfall compares month by month.

Month Oregano Needs Rainfall You Supplement Action
Jan 1.6" 0" ❄️ Dormant
Feb 1.8" 0" ❄️ Dormant
Mar 2.4" 0" ❄️ Dormant
Apr 1.3" 3.4" 0" ✅ Rainfall sufficient
May 1.3" 4.3" 0" ✅ Rainfall sufficient
Jun 1.3" 5.2" 0" ✅ Rainfall sufficient
Jul 1.3" 3.5" 0" ✅ Rainfall sufficient
Aug 1.3" 3.8" 0" ✅ Rainfall sufficient
Sep 1.3" 3.3" 0" ✅ Rainfall sufficient
Oct 1.3" 2.9" 0" ✅ Rainfall sufficient
Nov 2.8" 0" ❄️ Dormant
Dec 1.9" 0" ❄️ Dormant

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

Oregano 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.

Oregano needs ~1,144 GDD — county provides 2,912 GDD Excellent fit

Oregano Planting Timeline — Cass County, MO

Oregano Planting Calendar

Activity When Date Range
Transplant Outdoors April 21 Apr 21 – May 5
Harvest June 23 Jun 23 – Sep 1

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 Harvest
October
November
December

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.3"/week · Natural rainfall sufficient

📅 Days to Maturity

60–90 days

🧪 Soil pH

Needs 6–8 · Your soil: acceptable

🗺️ USDA Zone

Zone 6b

📆 Growing Season

191 days in Cass County

Growing Tips for Oregano in Cass County

Direct sow Oregano outdoors after April 14 in Cass County when soil has warmed and frost danger has passed.

General growing tips

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 Cass County, MO?

Cass County is in Zone 6b with an average last frost of April 14. Plan your Oregano planting based on this frost date — see the calendar above for exact timing.

What planting zone is Cass County, MO?

Cass County, Missouri is in USDA Hardiness Zone 6b. The average last spring frost is April 14 and first fall frost is October 22.

🌱

Your Cass County Garden Planner — Free

A 24-page printable planner built for Cass County (Zone 6b). 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 Cass County, MO. 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.