When to Plant Marjoram in Napa County, CA
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.
Napa County, California is in USDA Zone 9a. The average last spring frost is February 26 and the first fall frost is November 26, giving you a growing season of approximately 273 days.
At an elevation of 449 feet, Napa County receives approximately 35 inches of rainfall annually with predominantly loam soil. Summer highs average 88°F, providing good warmth for Marjoram during the growing season.
Napa County Soil Profile
Soil Type
Loam
Soil pH
6.7-7.5
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 Napa County
How your county's soil matches Marjoram's growing requirements.
Soil pH
Your soil pH (6.7–7.5) is within Marjoram's preferred range (6.5–7.5).
Soil Texture
The loam soil in Napa County is excellent for Marjoram — good drainage, moisture retention, and nutrient holding capacity.
Drainage
Drainage is adequate for Marjoram.
Organic Matter
Organic matter is moderate (3.0%). Annual compost additions will help Marjoram.
How to Plant Marjoram
Succession Planting Marjoram
Sow every 6.9 weeks. Last sowing by Aug 28 to harvest before frost.
Plant Water Budget
Water stress score is 6/10 — consider drought-tolerant varieties and mulching
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 | — | 7.5" | 0" | ❄️ Dormant |
| Feb | 1.3" | 7.8" | 0" | ✅ Rainfall sufficient |
| Mar | 1.3" | 5.8" | 0" | ✅ Rainfall sufficient |
| Apr | 1.3" | 2.3" | 0" | ✅ Rainfall sufficient |
| May | 1.3" | 0.8" | 0.5" | 💧 Light watering |
| Jun | 1.3" | 0.2" | 1.1" | 🚿 Regular watering |
| Jul | 1.3" | 0" | 1.3" | 🚿 Regular watering |
| Aug | 1.3" | 0" | 1.3" | 🚿 Regular watering |
| Sep | 1.3" | 0.3" | 1" | 🚿 Regular watering |
| Oct | 1.3" | 1.3" | 0" | ✅ Rainfall sufficient |
| Nov | 1.3" | 3.3" | 0" | ✅ Rainfall sufficient |
| Dec | — | 5.6" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Feb–Nov in Napa 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 — Napa County, CA
Marjoram 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 · Natural rainfall sufficient
📅 Days to Maturity
60–90 days
🧪 Soil pH
Needs 6.5–7.5 · Your soil: ideal
🗺️ USDA Zone
Zone 9a
📆 Growing Season
273 days in Napa County
Growing Tips for Marjoram in Napa County
Direct sow Marjoram outdoors after February 26 in Napa 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 Napa County, CA?
Napa County is in Zone 9a with an average last frost of February 26. Plan your Marjoram planting based on this frost date — see the calendar above for exact timing.
What planting zone is Napa County, CA?
Napa County, California is in USDA Hardiness Zone 9a. The average last spring frost is February 26 and first fall frost is November 26.
Plan Your Garden with Confidence
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