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When to Plant Rosemary in Calaveras County, CA

Calaveras County, California Zone 9a May

Your May game plan for Calaveras County, California

We've pulled the most time-sensitive tasks for Calaveras County, California this May and put them front and centre. Tackle them in order.

Avg. last frost April 8
Avg. first frost November 12
Soil temp (4") 68°F
Watering Critical
Pest pressure High
Daylight 14.1 hrs

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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.

Calaveras County, California is in USDA Zone 9a. The average last spring frost is April 8 and the first fall frost is November 12, giving you a growing season of approximately 218 days.

At an elevation of 2,363 feet, Calaveras County receives approximately 25 inches of rainfall annually with predominantly loam soil. Summer highs average 83°F, so choose short-season varieties of Rosemary to ensure they mature before fall.

Calaveras County, CA (Zone 9a) Long season
218 days
Last Spring Frost April 8
218 growing days
First Fall Frost November 12

Calaveras County Soil Profile

Soil Type

Loam

Soil pH

6.5-7.6

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (15 days to spare)
Transplant: Mar 9 🍅 Harvest: Jun 1 – Oct 19
Recommended (50%) ✗ May not fit
Transplant: Apr 15 🍅 Harvest: Jul 8 – Nov 25
Safe Start (90%) ✗ May not fit
Transplant: May 15 🍅 Harvest: Aug 7 – Dec 25

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 Calaveras County

How your county's soil matches Rosemary's growing requirements.

Soil pH

Your soil pH (6.5–7.6) overlaps with Rosemary's range (6.0–7.5), though not a perfect match.

Soil Texture

The loam soil in Calaveras County is excellent for Rosemary — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (2.9%). Annual compost additions will help Rosemary.

How to Plant Rosemary

0.5"
Planting Depth
8"
Between Plants
12"
Between Rows

Succession Planting Rosemary

3
successive plantings in your 218-day season

Sow every 9.1 weeks. Last sowing by May 16 to harvest before frost.

Plant Water Budget

Plant needs
0.3″/week
Rainfall provides
0.5″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Drought risk

Water stress score is 8/10 — 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 5.4" 0" ❄️ Dormant
Feb 4.8" 0" ❄️ Dormant
Mar 4" 0" ❄️ Dormant
Apr 1.3" 2.4" 0" ✅ Rainfall sufficient
May 1.3" 0.7" 0.6" 💧 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" 0.3" 💧 Light watering
Nov 1.3" 2.3" 0" ✅ Rainfall sufficient
Dec 3.9" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Nov in Calaveras 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 needs ~1,592 GDD — county provides 2,670 GDD Excellent fit

Rosemary Planting Timeline — Calaveras County, CA

Rosemary Planting Calendar

Activity When Date Range
Transplant Outdoors April 15 Apr 15 – Apr 29
Harvest July 8 Jul 8 – Nov 25

Plant 0.5" deep · 8" apart · Rows 12" apart

Month-by-Month Timeline

MonthActivities
January
February
March
April Transplant Outdoors
May
June
July Harvest
August Harvest
September Harvest
October Harvest
November Harvest
December

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.3"/week · Natural rainfall sufficient

📅 Days to Maturity

80–180 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 9a

📆 Growing Season

218 days in Calaveras County

Growing Tips for Rosemary in Calaveras County

Direct sow Rosemary outdoors after April 08 in Calaveras County when soil has warmed and frost danger has passed.

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 →

Frequently Asked Questions

When should I plant Rosemary in Calaveras County, CA?

Calaveras County is in Zone 9a with an average last frost of April 8. Plan your Rosemary planting based on this frost date — see the calendar above for exact timing.

What planting zone is Calaveras County, CA?

Calaveras County, California is in USDA Hardiness Zone 9a. The average last spring frost is April 8 and first fall frost is November 12.

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Your Calaveras County Garden Planner — Free

A 24-page printable planner built for Calaveras County (Zone 9a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

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Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Calaveras County, CA. Local conditions may vary. Last updated: May 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.