Blog

When to Plant Rosemary in Galveston County, TX

Galveston County, Texas Zone 9b May

May in the garden — Galveston County, Texas

Your garden in Galveston County, Texas is working on a schedule, even when you're not. Here's where you should be this May.

Avg. last frost February 5
Avg. first frost December 7
Soil temp (4") 76°F
Watering Low
Pest pressure High
Daylight 13.5 hrs
  1. Collect rosemary at their peak

    Don't tug. Use scissors or pruners for clean cuts — torn stems invite disease.

Coming up in June — start thinking about
  • First harvests: rosemary

Instant PDF download. No spam, unsubscribe any time.

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.

Galveston County, Texas is in USDA Zone 9b. The average last spring frost is February 5 and the first fall frost is December 7, giving you a growing season of approximately 305 days.

At an elevation of 9 feet, Galveston County receives approximately 72.5 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 100°F, so Rosemary may need afternoon shade and extra watering during peak heat. 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.

Galveston County, TX (Zone 9b) Year-round
305 days
Last Spring Frost February 5
305 growing days
First Fall Frost December 7

Galveston County Soil Profile

Soil Type

Sandy Loam

Soil pH

5.7-6.5

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (86 days to spare)
Transplant: Jan 25 🍅 Harvest: Apr 19 – Sep 6
Recommended (50%) ✓ Fits season (74 days to spare)
Transplant: Feb 12 🍅 Harvest: May 7 – Sep 24
Safe Start (90%) ✓ Fits season (61 days to spare)
Transplant: Mar 13 🍅 Harvest: Jun 5 – Oct 23

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 Galveston County

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

Soil pH

Your soil pH (5.7–6.5) overlaps with Rosemary's range (6.0–7.5), though not a perfect match.

Soil Texture

Sandy soil in Galveston County warms quickly in spring but drains fast. Rosemary will need more frequent watering and regular compost additions to retain nutrients.

Organic Matter

Organic matter is moderate (2.1%). Annual compost additions will help Rosemary.

How to Plant Rosemary

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

Succession Planting Rosemary

4
successive plantings in your 305-day season

Sow every 9.1 weeks. Last sowing by Jun 10 to harvest before frost.

Plant Water Budget

Plant needs
0.3″/week
Rainfall provides
1.0″/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 2.1" 0" ❄️ Dormant
Feb 1.3" 2.2" 0" ✅ Rainfall sufficient
Mar 1.3" 5.4" 0" ✅ Rainfall sufficient
Apr 1.3" 8.2" 0" ✅ Rainfall sufficient
May 1.3" 10.4" 0" ✅ Rainfall sufficient
Jun 1.3" 10.9" 0" ✅ Rainfall sufficient
Jul 1.3" 8.7" 0" ✅ Rainfall sufficient
Aug 1.3" 8.6" 0" ✅ Rainfall sufficient
Sep 1.3" 6.2" 0" ✅ Rainfall sufficient
Oct 1.3" 5.2" 0" ✅ Rainfall sufficient
Nov 1.3" 2.6" 0" ✅ Rainfall sufficient
Dec 1.3" 1.9" 0" ✅ Rainfall sufficient

Water needs are for active growing months only (Feb–Dec in Galveston 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 ~3,250 GDD — county provides 7,650 GDD Excellent fit

Rosemary Planting Timeline — Galveston County, TX

Rosemary Planting Calendar

Activity When Date Range
Transplant Outdoors February 12 Feb 12 – Feb 26
Harvest May 7 May 7 – Sep 24

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

Month-by-Month Timeline

MonthActivities
January
February Transplant Outdoors
March
April
May Harvest
June Harvest
July Harvest
August Harvest
September Harvest
October
November
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 9b

📆 Growing Season

305 days in Galveston County

Growing Tips for Rosemary in Galveston County

Direct sow Rosemary outdoors after February 05 in Galveston County when soil has warmed and frost danger has passed.

Sandy soil in Galveston 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 summer highs reaching 100°F in Galveston County, provide afternoon shade for Rosemary and water deeply in the morning.

With 72" of annual rainfall in Galveston 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 Galveston County, TX?

Galveston County is in Zone 9b with an average last frost of February 5. Plan your Rosemary planting based on this frost date — see the calendar above for exact timing.

What planting zone is Galveston County, TX?

Galveston County, Texas is in USDA Hardiness Zone 9b. The average last spring frost is February 5 and first fall frost is December 7.

🌱

Your Galveston County Garden Planner — Free

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

Instant PDF download. No spam, unsubscribe any time.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Galveston County, TX. 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.