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When to Plant Rosemary in St. Lucie County, FL

St. Lucie County, Florida Zone 10a May

Top priorities for St. Lucie County, Florida gardeners in May

A quick May briefing for St. Lucie County, Florida gardeners — what's urgent, what's next, and what can wait.

Avg. last frost January 29
Avg. first frost December 16
Soil temp (4") 78°F
Watering Moderate
Pest pressure High
Daylight 13.4 hrs
  1. Collect rosemary at their peak

    Morning harvests are best — cooler temperatures mean crisper produce and longer fridge life.

A few tasks this May that'll pay off in June
  • 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. Lucie County, Florida is in USDA Zone 10a. The average last spring frost is January 29 and the first fall frost is December 16, giving you a growing season of approximately 321 days.

At an elevation of 185 feet, St. Lucie County receives approximately 56.2 inches of rainfall annually with predominantly sand soil. Summer highs average 89°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. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Rosemary root diseases.

St. Lucie County, FL (Zone 10a) Year-round
321 days
Last Spring Frost January 29
321 growing days
First Fall Frost December 16
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St. Lucie County Soil Profile

Soil Type

Sand

Soil pH

4.8-5.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (93 days to spare)
Transplant: Jan 26 🍅 Harvest: Apr 20 – Sep 7
Recommended (50%) ✓ Fits season (90 days to spare)
Transplant: Feb 5 🍅 Harvest: Apr 30 – Sep 17
Safe Start (90%) ✓ Fits season (77 days to spare)
Transplant: Feb 25 🍅 Harvest: May 20 – Oct 7

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. Lucie County

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

Soil pH

Your soil pH (4.8–5.8) is more acidic than Rosemary prefers (6.0–7.5). Add garden lime to raise pH.

Soil Texture

Sandy soil in St. Lucie 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 (1.3%). Add 2-3 inches of compost before planting Rosemary.

How to Plant Rosemary

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

Succession Planting Rosemary

4
successive plantings in your 321-day season

Sow every 9.1 weeks. Last sowing by Jun 19 to harvest before frost.

Plant Water Budget

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

Water stress score is 6/10 — 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 1.3" 2.3" 0" ✅ Rainfall sufficient
Feb 1.3" 2.7" 0" ✅ Rainfall sufficient
Mar 1.3" 3.3" 0" ✅ Rainfall sufficient
Apr 1.3" 2.2" 0" ✅ Rainfall sufficient
May 1.3" 3.1" 0" ✅ Rainfall sufficient
Jun 1.3" 8.1" 0" ✅ Rainfall sufficient
Jul 1.3" 9" 0" ✅ Rainfall sufficient
Aug 1.3" 8.6" 0" ✅ Rainfall sufficient
Sep 1.3" 7.5" 0" ✅ Rainfall sufficient
Oct 1.3" 5" 0" ✅ Rainfall sufficient
Nov 1.3" 2.1" 0" ✅ Rainfall sufficient
Dec 1.3" 2.2" 0" ✅ Rainfall sufficient

Water needs are for active growing months only (Jan–Dec in St. Lucie 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 5,393 GDD Excellent fit

Rosemary Planting Timeline — St. Lucie County, FL

Rosemary Planting Calendar

Activity When Date Range
Transplant Outdoors February 5 Feb 5 – Feb 19
Harvest April 30 Apr 30 – Sep 17

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

Month-by-Month Timeline

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

🗺️ USDA Zone

Zone 10a

📆 Growing Season

321 days in St. Lucie County

Growing Tips for Rosemary in St. Lucie County

Direct sow Rosemary outdoors after January 29 in St. Lucie County when soil has warmed and frost danger has passed.

Sandy soil in St. Lucie County dries quickly — mulch Rosemary with 2-3 inches of straw and water deeply 2-3 times per week rather than lightly every day.

With 56" of annual rainfall in St. Lucie County, ensure good drainage for Rosemary — excess moisture can promote root rot and fungal diseases.

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. Lucie County, FL?

St. Lucie County is in Zone 10a with an average last frost of January 29. Plan your Rosemary planting based on this frost date — see the calendar above for exact timing.

What planting zone is St. Lucie County, FL?

St. Lucie County, Florida is in USDA Hardiness Zone 10a. The average last spring frost is January 29 and first fall frost is December 16.

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Your St. Lucie County Garden Planner — Free

A 24-page printable planner built for St. Lucie County (Zone 10a). 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. Lucie County, FL. 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.