When to Plant Oregano in Whitman County, WA
Whitman County, Washington gardeners: here's your May plan
May rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Whitman County, Washington.
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Plant out oregano
Plant tomatoes deep — bury the stem up to the first true leaves to grow extra roots. Everything else goes in at the same depth it grew in the tray.
Oregano is a robust perennial herb essential to Italian and Greek cuisine. Its pungent, savory leaves intensify in flavor when dried.
Whitman County, Washington is in USDA Zone 6b. The average last spring frost is May 10 and the first fall frost is September 29, giving you a growing season of approximately 142 days.
At an elevation of 1,541 feet, Whitman County receives approximately 14.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 88°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.
Whitman County Soil Profile
Soil Type
Silt Loam
Soil pH
5.5-6.7
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 Whitman County
How your county's soil matches Oregano's growing requirements.
Soil pH
Your soil pH (5.5–6.7) overlaps with Oregano's range (6.0–8.0), though not a perfect match.
Soil Texture
The silt loam soil in Whitman County is excellent for Oregano — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (5.0%) — Oregano will thrive.
How to Plant Oregano
Succession Planting Oregano
Sow every 6.9 weeks. Last sowing by Jul 01 to harvest before frost.
Plant Water Budget
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 | — | 2.2" | 0" | ❄️ Dormant |
| Feb | — | 1.5" | 0" | ❄️ Dormant |
| Mar | — | 1.3" | 0" | ❄️ Dormant |
| Apr | — | 1.2" | 0" | ❄️ Dormant |
| May | 1.3" | 0.8" | 0.5" | 💧 Light watering |
| Jun | 1.3" | 0.6" | 0.7" | 🚿 Regular watering |
| Jul | 1.3" | 0.3" | 1" | 🚿 Regular watering |
| Aug | 1.3" | 0.2" | 1.1" | 🚿 Regular watering |
| Sep | 1.3" | 0.6" | 0.7" | 🚿 Regular watering |
| Oct | — | 1.3" | 0" | ❄️ Dormant |
| Nov | — | 2.2" | 0" | ❄️ Dormant |
| Dec | — | 2.5" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Sep in Whitman 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 — Whitman County, WA
Oregano Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Transplant Outdoors | May 17 | May 17 – May 31 |
| Harvest | July 19 | Jul 19 – Sep 27 |
Plant 0.5" deep · 8" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | — |
| May | Transplant Outdoors |
| June | — |
| 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
142 days in Whitman County
Growing Tips for Oregano in Whitman County
Direct sow Oregano outdoors after May 10 in Whitman 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 Whitman County, WA?
Whitman County is in Zone 6b with an average last frost of May 10. Plan your Oregano planting based on this frost date — see the calendar above for exact timing.
What planting zone is Whitman County, WA?
Whitman County, Washington is in USDA Hardiness Zone 6b. The average last spring frost is May 10 and first fall frost is September 29.
Your Whitman County Garden Planner — Free
A 24-page printable planner built for Whitman 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.