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When to Plant Rosemary in St. Clair County, AL

St. Clair County, Alabama Zone 8a May

This month in St. Clair County, Alabama

May is a pivotal month for St. Clair County, Alabama gardens. Focus on these tasks first and you'll set up the rest of the season for success.

Avg. last frost March 27
Avg. first frost November 1
Soil temp (4") 67°F
Watering Moderate
Pest pressure Moderate
Daylight 13.7 hrs
Before June arrives, get these ready
  • First harvests: rosemary

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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.

St. Clair County, Alabama is in USDA Zone 8a. The average last spring frost is March 27 and the first fall frost is November 1, giving you a growing season of approximately 219 days.

At an elevation of 211 feet, St. Clair County receives approximately 48.4 inches of rainfall annually with predominantly clay loam soil. Summer highs average 89°F, providing good warmth for Rosemary during the growing season. Clay soil retains moisture well for Rosemary, but amend with compost to improve drainage and prevent root rot.

St. Clair County, AL (Zone 8a) Long season
219 days
Last Spring Frost March 27
219 growing days
First Fall Frost November 1
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St. Clair County Soil Profile

Soil Type

Clay Loam

Soil pH

5.3-6.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Transplant: Mar 27 🍅 Harvest: Jun 19 – Nov 6
Recommended (50%) ✗ May not fit
Transplant: Apr 3 🍅 Harvest: Jun 26 – Nov 13
Safe Start (90%) ✗ May not fit
Transplant: Apr 22 🍅 Harvest: Jul 15 – Dec 2

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 St. Clair County

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

Soil pH

Your soil pH (5.3–6.8) overlaps with Rosemary's range (6.0–7.5), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.7%). 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 219-day season

Sow every 9.1 weeks. Last sowing by May 05 to harvest before frost.

Plant Water Budget

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

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 3.9" 0" ❄️ Dormant
Feb 3.6" 0" ❄️ Dormant
Mar 1.3" 4.3" 0" ✅ Rainfall sufficient
Apr 1.3" 3.8" 0" ✅ Rainfall sufficient
May 1.3" 3.7" 0" ✅ Rainfall sufficient
Jun 1.3" 4.8" 0" ✅ Rainfall sufficient
Jul 1.3" 4.8" 0" ✅ Rainfall sufficient
Aug 1.3" 4.4" 0" ✅ Rainfall sufficient
Sep 1.3" 4.3" 0" ✅ Rainfall sufficient
Oct 1.3" 3.6" 0" ✅ Rainfall sufficient
Nov 1.3" 3.4" 0" ✅ Rainfall sufficient
Dec 3.7" 0" ❄️ Dormant

Water needs are for active growing months only (Mar–Nov in St. Clair 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 ~2,178 GDD — county provides 3,668 GDD Excellent fit

Rosemary Planting Timeline — St. Clair County, AL

Rosemary Planting Calendar

Activity When Date Range
Transplant Outdoors April 3 Apr 3 – Apr 17
Harvest June 26 Jun 26 – Nov 13

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

Month-by-Month Timeline

MonthActivities
January
February
March
April Transplant Outdoors
May
June Harvest
July Harvest
August Harvest
September Harvest
October Harvest
November Harvest
December
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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 8a

📆 Growing Season

219 days in St. Clair County

Growing Tips for Rosemary in St. Clair County

Direct sow Rosemary outdoors after March 27 in St. Clair County when soil has warmed and frost danger has passed.

With St. Clair County's clay soil (26% clay), work in 3-4 inches of compost before planting Rosemary. Avoid tilling when soil is wet to prevent compaction.

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 St. Clair County, AL?

St. Clair County is in Zone 8a with an average last frost of March 27. Plan your Rosemary planting based on this frost date — see the calendar above for exact timing.

What planting zone is St. Clair County, AL?

St. Clair County, Alabama is in USDA Hardiness Zone 8a. The average last spring frost is March 27 and first fall frost is November 1.

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Your St. Clair County Garden Planner — Free

A 24-page printable planner built for St. Clair County (Zone 8a). 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 St. Clair County, AL. 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.