When to Plant Rosemary in Castro County, TX
Your May game plan for Castro County, Texas
Your Castro County, Texas garden is entering a new phase. Here's what's on the schedule for May and why each task matters now.
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.
Castro County, Texas is in USDA Zone 7a. The average last spring frost is April 14 and the first fall frost is October 24, giving you a growing season of approximately 193 days.
At an elevation of 3,838 feet, Castro County receives approximately 47.6 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 95°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.
Castro County Soil Profile
Soil Type
Sandy Loam
Soil pH
7.5-8.1
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 Castro County
How your county's soil matches Rosemary's growing requirements.
Soil pH
Your soil pH (7.5–8.1) is more alkaline than Rosemary prefers (6.0–7.5). Add sulfur or peat moss to lower pH.
Soil Texture
Sandy soil in Castro 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 low (1.0%). Add 2-3 inches of compost before planting Rosemary.
How to Plant Rosemary
Succession Planting Rosemary
Sow every 9.1 weeks. Last sowing by Apr 27 to harvest before frost.
Plant Water Budget
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 | — | 3.3" | 0" | ❄️ Dormant |
| Feb | — | 2.7" | 0" | ❄️ Dormant |
| Mar | — | 2.4" | 0" | ❄️ Dormant |
| Apr | 1.3" | 1.7" | 0" | ✅ Rainfall sufficient |
| May | 1.3" | 1.2" | 0.1" | 💧 Light watering |
| Jun | 1.3" | 1.5" | 0" | ✅ Rainfall sufficient |
| Jul | 1.3" | 8" | 0" | ✅ Rainfall sufficient |
| Aug | 1.3" | 8.9" | 0" | ✅ Rainfall sufficient |
| Sep | 1.3" | 6.8" | 0" | ✅ Rainfall sufficient |
| Oct | 1.3" | 4.9" | 0" | ✅ Rainfall sufficient |
| Nov | — | 2.5" | 0" | ❄️ Dormant |
| Dec | — | 3.7" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Castro 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 — Castro County, TX
Rosemary Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Transplant Outdoors | April 21 | Apr 21 – May 5 |
| Harvest | July 14 | Jul 14 – Dec 1 |
Plant 0.5" deep · 8" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | Transplant Outdoors |
| May | Transplant Outdoors |
| June | — |
| July | Harvest |
| August | Harvest |
| September | Harvest |
| October | Harvest |
| November | Harvest |
| December | Harvest |
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_alkaline
🗺️ USDA Zone
Zone 7a
📆 Growing Season
193 days in Castro County
Growing Tips for Rosemary in Castro County
Direct sow Rosemary outdoors after April 14 in Castro County when soil has warmed and frost danger has passed.
Sandy soil in Castro County dries quickly — mulch Rosemary with 2-3 inches of straw and water deeply 2-3 times per week rather than lightly every day.
Your 193.0-day growing season in Castro County is tight for Rosemary (80.0-180.0 days to maturity). Start indoors and choose early-maturing varieties.
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 Castro County, TX?
Castro County is in Zone 7a with an average last frost of April 14. Plan your Rosemary planting based on this frost date — see the calendar above for exact timing.
What planting zone is Castro County, TX?
Castro County, Texas is in USDA Hardiness Zone 7a. The average last spring frost is April 14 and first fall frost is October 24.
Your Castro County Garden Planner — Free
A 24-page printable planner built for Castro County (Zone 7a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.