When to Plant Rosemary in Harris County, TX
Your May gardening checklist
Each item below is timed to Harris County, Texas's frost dates and soil temperatures. Skip nothing, stress about nothing.
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Bring in the rosemary
Morning harvests are best — cooler temperatures mean crisper produce and longer fridge life.
Before June arrives, get these ready
- First harvests: rosemary
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.
Harris County, Texas is in USDA Zone 9b. The average last spring frost is February 14 and the first fall frost is December 4, giving you a growing season of approximately 293 days.
At an elevation of 390 feet, Harris County receives approximately 67.7 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 102°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.
Harris County Soil Profile
Soil Type
Sandy Loam
Soil pH
5.3-6.5
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 Harris County
How your county's soil matches Rosemary's growing requirements.
Soil pH
Your soil pH (5.3–6.5) is more acidic than Rosemary prefers (6.0–7.5). Add garden lime to raise pH.
Soil Texture
Sandy soil in Harris 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 (2.2%). Annual compost additions will help Rosemary.
How to Plant Rosemary
Succession Planting Rosemary
Sow every 9.1 weeks. Last sowing by Jun 07 to harvest before frost.
Plant Water Budget
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 | — | 1.6" | 0" | ❄️ Dormant |
| Feb | 1.3" | 2.7" | 0" | ✅ Rainfall sufficient |
| Mar | 1.3" | 3.8" | 0" | ✅ Rainfall sufficient |
| Apr | 1.3" | 7.4" | 0" | ✅ Rainfall sufficient |
| May | 1.3" | 10.1" | 0" | ✅ Rainfall sufficient |
| Jun | 1.3" | 10" | 0" | ✅ Rainfall sufficient |
| Jul | 1.3" | 9.6" | 0" | ✅ Rainfall sufficient |
| Aug | 1.3" | 8.5" | 0" | ✅ Rainfall sufficient |
| Sep | 1.3" | 6.3" | 0" | ✅ Rainfall sufficient |
| Oct | 1.3" | 3.9" | 0" | ✅ Rainfall sufficient |
| Nov | 1.3" | 2.2" | 0" | ✅ Rainfall sufficient |
| Dec | 1.3" | 1.6" | 0" | ✅ Rainfall sufficient |
Water needs are for active growing months only (Feb–Dec in Harris 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 — Harris County, TX
Rosemary Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Transplant Outdoors | February 21 | Feb 21 – Mar 7 |
| Harvest | May 16 | May 16 – Oct 3 |
Plant 0.5" deep · 8" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | Transplant Outdoors |
| March | Transplant Outdoors |
| April | — |
| May | Harvest |
| June | Harvest |
| July | Harvest |
| August | Harvest |
| September | Harvest |
| October | Harvest |
| 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: too_acidic
🗺️ USDA Zone
Zone 9b
📆 Growing Season
293 days in Harris County
Growing Tips for Rosemary in Harris County
Direct sow Rosemary outdoors after February 14 in Harris County when soil has warmed and frost danger has passed.
Sandy soil in Harris 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 102°F in Harris County, provide afternoon shade for Rosemary and water deeply in the morning.
With 68" of annual rainfall in Harris 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 →
Rosemary in Other Locations
Frequently Asked Questions
When should I plant Rosemary in Harris County, TX?
Harris County is in Zone 9b with an average last frost of February 14. Plan your Rosemary planting based on this frost date — see the calendar above for exact timing.
What planting zone is Harris County, TX?
Harris County, Texas is in USDA Hardiness Zone 9b. The average last spring frost is February 14 and first fall frost is December 4.
Your Harris County Garden Planner — Free
A 24-page printable planner built for Harris 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.