When to Plant Marjoram in Union County, OR
What to do in May
If you only do a handful of things in the garden this May, make it these. They're sequenced around your zone's frost timing.
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Move marjoram into the garden
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.
Sweet marjoram is a tender perennial herb with a delicate, sweet oregano-like flavor. It is a cornerstone of Mediterranean cooking and pairs well with meats and vegetables.
Union County, Oregon is in USDA Zone 6b. The average last spring frost is May 12 and the first fall frost is September 26, giving you a growing season of approximately 137 days.
At an elevation of 2,751 feet, Union County receives approximately 23.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 86°F, providing good warmth for Marjoram during the growing season.
Union County Soil Profile
Soil Type
Silt Loam
Soil pH
5.2-6.6
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 Union County
How your county's soil matches Marjoram's growing requirements.
Soil pH
Your soil pH (5.2–6.6) is more acidic than Marjoram prefers (6.5–7.5). Add garden lime to raise pH.
Soil Texture
The silt loam soil in Union County is excellent for Marjoram — good drainage, moisture retention, and nutrient holding capacity.
Drainage
Drainage is adequate for Marjoram.
Organic Matter
Organic matter is excellent (5.6%) — Marjoram will thrive.
How to Plant Marjoram
Succession Planting Marjoram
Sow every 6.9 weeks. Last sowing by Jun 28 to harvest before frost.
Plant Water Budget
Monthly Watering Guide for Marjoram
Marjoram 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 | Marjoram Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 2.9" | 0" | ❄️ Dormant |
| Feb | — | 2.6" | 0" | ❄️ Dormant |
| Mar | — | 2.3" | 0" | ❄️ Dormant |
| Apr | — | 1.5" | 0" | ❄️ Dormant |
| May | 1.3" | 1.5" | 0" | ✅ Rainfall sufficient |
| Jun | 1.3" | 0.9" | 0.4" | 💧 Light watering |
| Jul | 1.3" | 0.4" | 0.9" | 🚿 Regular watering |
| Aug | 1.3" | 0.5" | 0.8" | 🚿 Regular watering |
| Sep | 1.3" | 1" | 0.3" | 💧 Light watering |
| Oct | — | 2" | 0" | ❄️ Dormant |
| Nov | — | 3.8" | 0" | ❄️ Dormant |
| Dec | — | 4.2" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Sep in Union County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Marjoram 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.
Marjoram Planting Timeline — Union County, OR
Marjoram Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Transplant Outdoors | May 19 | May 19 – Jun 2 |
| Harvest | July 21 | Jul 21 – Sep 29 |
Plant 0.5" deep · 8" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | — |
| May | Transplant Outdoors |
| June | Transplant Outdoors |
| 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 6.5–7.5 · Your soil: too_acidic
🗺️ USDA Zone
Zone 6b
📆 Growing Season
137 days in Union County
Growing Tips for Marjoram in Union County
Direct sow Marjoram outdoors after May 12 in Union County when soil has warmed and frost danger has passed.
General growing tips
Start seeds indoors 6-8 weeks before last frost. Harvest stems just as flower buds appear for peak flavor. In cold climates, grow as an annual or bring containers indoors.
Companion Planting
Good Companions
Check more plant combinations with our Companion Planting Checker →
Marjoram in Other Locations
Frequently Asked Questions
When should I plant Marjoram in Union County, OR?
Union County is in Zone 6b with an average last frost of May 12. Plan your Marjoram planting based on this frost date — see the calendar above for exact timing.
What planting zone is Union County, OR?
Union County, Oregon is in USDA Hardiness Zone 6b. The average last spring frost is May 12 and first fall frost is September 26.
Your Union County Garden Planner — Free
A 24-page printable planner built for Union 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.