When to Plant Rosemary in Los Alamos County, NM
What to do in May
May rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Los Alamos County, New Mexico.
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Set out rosemary seedlings
Frost risk is low now in Los Alamos County, New Mexico. If you've been covering beds overnight, you can stop.
Rosemary is an aromatic evergreen shrub with needle-like leaves and a piney, citrus flavor. It is a Mediterranean herb that thrives in warm, dry conditions.
Los Alamos County, New Mexico is in USDA Zone 7a. The average last spring frost is May 10 and the first fall frost is October 7, giving you a growing season of approximately 150 days.
At an elevation of 5,220 feet, Los Alamos County receives approximately 12.1 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 87°F, providing good warmth for Rosemary during the growing season. Sandy soil warms quickly in spring — great for early planting — but Rosemary will need more frequent watering and organic matter to retain nutrients. With low rainfall, drip irrigation is essential for growing Rosemary successfully. Mulch heavily to conserve soil moisture.
Los Alamos County Soil Profile
Soil Type
Sandy Loam
Soil pH
7-8.6
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 Los Alamos County
How your county's soil matches Rosemary's growing requirements.
Soil pH
Your soil pH (7.0–8.6) is more alkaline than Rosemary prefers (6.0–7.5). Add sulfur or peat moss to lower pH.
Soil Texture
Sandy soil in Los Alamos County warms quickly in spring but drains fast. Rosemary will need more frequent watering and regular compost additions to retain nutrients.
Drainage
Drainage is adequate for Rosemary.
Organic Matter
Organic matter is low (0.8%). Add 2-3 inches of compost before planting Rosemary.
How to Plant Rosemary
Succession Planting Rosemary
Sow every 9.1 weeks. Last sowing by Apr 10 to harvest before frost.
Plant Water Budget
Water stress score is 10/10 — consider drought-tolerant varieties and mulching
Monthly Watering Guide for Rosemary
Rosemary 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 | Rosemary Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 0.9" | 0" | ❄️ Dormant |
| Feb | — | 0.6" | 0" | ❄️ Dormant |
| Mar | — | 0.8" | 0" | ❄️ Dormant |
| Apr | — | 0.4" | 0" | ❄️ Dormant |
| May | 1.3" | 0.3" | 1" | 🚿 Regular watering |
| Jun | 1.3" | 0.4" | 0.9" | 🚿 Regular watering |
| Jul | 1.3" | 1.9" | 0" | ✅ Rainfall sufficient |
| Aug | 1.3" | 2.4" | 0" | ✅ Rainfall sufficient |
| Sep | 1.3" | 1.7" | 0" | ✅ Rainfall sufficient |
| Oct | 1.3" | 1.1" | 0.2" | 💧 Light watering |
| Nov | — | 0.7" | 0" | ❄️ Dormant |
| Dec | — | 0.8" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Oct in Los Alamos County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Rosemary 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.
Rosemary Planting Timeline — Los Alamos County, NM
Rosemary Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Transplant Outdoors | May 17 | May 17 – May 31 |
| Harvest | August 9 | Aug 9 – Dec 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 | — |
| August | Harvest |
| September | Harvest |
| October | Harvest |
| November | Harvest |
| December | Harvest |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
0.3"/week · Only during dry spells
📅 Days to Maturity
80–180 days
🧪 Soil pH
Needs 6–7.5 · Your soil: too_alkaline
🗺️ USDA Zone
Zone 7a
📆 Growing Season
150 days in Los Alamos County
Growing Tips for Rosemary in Los Alamos County
Direct sow Rosemary outdoors after May 10 in Los Alamos County when soil has warmed and frost danger has passed.
Sandy soil in Los Alamos County dries quickly — mulch Rosemary with 2-3 inches of straw and water deeply 2-3 times per week rather than lightly every day.
Your 150.0-day growing season in Los Alamos County is tight for Rosemary (80.0-180.0 days to maturity). Start indoors and choose early-maturing varieties.
General growing tips
Grow in well-drained soil and avoid overwatering. In cold climates, grow in containers and bring indoors for winter. Propagate from stem cuttings for faster results than seed.
Companion Planting
Good Companions
Check more plant combinations with our Companion Planting Checker →
Rosemary in Other Locations
Frequently Asked Questions
When should I plant Rosemary in Los Alamos County, NM?
Los Alamos County is in Zone 7a with an average last frost of May 10. Plan your Rosemary planting based on this frost date — see the calendar above for exact timing.
What planting zone is Los Alamos County, NM?
Los Alamos County, New Mexico is in USDA Hardiness Zone 7a. The average last spring frost is May 10 and first fall frost is October 7.
Your Los Alamos County Garden Planner — Free
A 24-page printable planner built for Los Alamos County (Zone 7a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.