When to Plant Oregano in Contra Costa County, CA
Contra Costa County, California gardeners: here's your May plan
Your garden in Contra Costa County, California is working on a schedule, even when you're not. Here's where you should be this May.
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Collect oregano at their peak
If you can't use it all right away, check the food-preservation section of your planner.
June will be here before you know it — start on
- First harvests: oregano
Oregano is a robust perennial herb essential to Italian and Greek cuisine. Its pungent, savory leaves intensify in flavor when dried.
Contra Costa County, California is in USDA Zone 9b. The average last spring frost is February 26 and the first fall frost is November 29, giving you a growing season of approximately 276 days.
At an elevation of 88 feet, Contra Costa County receives approximately 19 inches of rainfall annually with predominantly loam soil. Summer highs average 93°F, providing good warmth for Oregano during the growing season. With low rainfall, drip irrigation is essential for growing Oregano successfully. Mulch heavily to conserve soil moisture.
Contra Costa County Soil Profile
Soil Type
Loam
Soil pH
6.7-7.8
Drainage
Well Drained
Plant Planting Risk Windows
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 Contra Costa County
How your county's soil matches Oregano's growing requirements.
Soil pH
Your soil pH (6.7–7.8) is within Oregano's preferred range (6.0–8.0).
Soil Texture
The loam soil in Contra Costa County is excellent for Oregano — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (3.0%). Annual compost additions will help Oregano.
How to Plant Oregano
Succession Planting Oregano
Sow every 6.9 weeks. Last sowing by Aug 31 to harvest before frost.
Plant Water Budget
Water stress score is 8/10 — consider drought-tolerant varieties and mulching
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 | — | 4.1" | 0" | ❄️ Dormant |
| Feb | 1.3" | 4.5" | 0" | ✅ Rainfall sufficient |
| Mar | 1.3" | 3" | 0" | ✅ Rainfall sufficient |
| Apr | 1.3" | 1.5" | 0" | ✅ Rainfall sufficient |
| May | 1.3" | 0.6" | 0.7" | 🚿 Regular watering |
| Jun | 1.3" | 0.1" | 1.2" | 🚿 Regular watering |
| Jul | 1.3" | 0" | 1.3" | 🚿 Regular watering |
| Aug | 1.3" | 0" | 1.3" | 🚿 Regular watering |
| Sep | 1.3" | 0.2" | 1.1" | 🚿 Regular watering |
| Oct | 1.3" | 0.7" | 0.6" | 💧 Light watering |
| Nov | 1.3" | 1.6" | 0" | ✅ Rainfall sufficient |
| Dec | — | 2.7" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Feb–Nov in Contra Costa 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 Planting Timeline — Contra Costa County, CA
Oregano Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Transplant Outdoors | March 5 | Mar 5 – Mar 19 |
| Harvest | May 7 | May 7 – Jul 16 |
Plant 0.5" deep · 8" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Transplant Outdoors |
| April | — |
| May | Harvest |
| June | Harvest |
| July | Harvest |
| August | — |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
0.3"/week · Only during dry spells
📅 Days to Maturity
60–90 days
🧪 Soil pH
Needs 6–8 · Your soil: ideal
🗺️ USDA Zone
Zone 9b
📆 Growing Season
276 days in Contra Costa County
Growing Tips for Oregano in Contra Costa County
Direct sow Oregano outdoors after February 26 in Contra Costa 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 →
Oregano in Other Locations
Frequently Asked Questions
When should I plant Oregano in Contra Costa County, CA?
Contra Costa County is in Zone 9b with an average last frost of February 26. Plan your Oregano planting based on this frost date — see the calendar above for exact timing.
What planting zone is Contra Costa County, CA?
Contra Costa County, California is in USDA Hardiness Zone 9b. The average last spring frost is February 26 and first fall frost is November 29.
Your Contra Costa County Garden Planner — Free
A 24-page printable planner built for Contra Costa County (Zone 9b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.