When to Plant Vinca (Annual) in Shelby County, TX
Annual vinca (Catharanthus roseus), also called Madagascar periwinkle, is one of the most heat- and drought-tolerant bedding plants available. Glossy foliage stays attractive all season while cheerful pinwheel blooms continue without deadheading. A top performer in hot, humid Southern summers where impatiens and begonias struggle. Self-cleaning; requires little maintenance once established.
Shelby County, Texas is in USDA Zone 8b. The average last spring frost is March 6 and the first fall frost is November 16, giving you a growing season of approximately 255 days.
At an elevation of 251 feet, Shelby County receives approximately 63.8 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 94°F, providing good warmth for Vinca (Annual) during the growing season. Sandy soil warms quickly in spring — great for early planting — but Vinca (Annual) will need more frequent watering and organic matter to retain nutrients. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Vinca (Annual) root diseases.
Shelby County Soil Profile
Soil Type
Sandy Loam
Soil pH
5.6-6.3
Drainage
Well Drained
Monthly Watering Guide for Vinca (Annual)
Vinca (Annual) needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.
| Month | Vinca (Annual) Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1.7" | 0" | ❄️ Dormant |
| Feb | — | 2.2" | 0" | ❄️ Dormant |
| Mar | 4.3" | 4.3" | 0" | ✅ Rainfall sufficient |
| Apr | 4.3" | 5.7" | 0" | ✅ Rainfall sufficient |
| May | 4.3" | 9.5" | 0" | ✅ Rainfall sufficient |
| Jun | 4.3" | 10.1" | 0" | ✅ Rainfall sufficient |
| Jul | 4.3" | 9.1" | 0" | ✅ Rainfall sufficient |
| Aug | 4.3" | 7.5" | 0" | ✅ Rainfall sufficient |
| Sep | 4.3" | 5.9" | 0" | ✅ Rainfall sufficient |
| Oct | 4.3" | 3.9" | 0.4" | 💧 Light watering |
| Nov | 4.3" | 2.4" | 1.9" | 💧 Light watering |
| Dec | — | 1.4" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Mar–Nov in Shelby County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Vinca (Annual) Planting Timeline — Shelby County, TX
Vinca (Annual) Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | December 26 | Dec 26 – Jan 9 |
| Transplant Outdoors | February 20 | Feb 20 – Mar 6 |
| Bloom | May 1 | May 1 – Oct 2 |
Plant 0.1" deep · 10" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | Start Indoors |
| February | Transplant Outdoors |
| March | Transplant Outdoors |
| April | — |
| May | Bloom |
| June | Bloom |
| July | Bloom |
| August | Bloom |
| September | Bloom |
| October | Bloom |
| November | — |
| December | Start Indoors |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
Low — drought tolerant
📅 Days to Maturity
70–90 days
🧪 Soil pH
Needs 6–7 · Your soil: N/A
🗺️ USDA Zone
Zone 8b
📆 Growing Season
255 days in Shelby County
Growing Tips for Shelby County
Start seeds indoors 10–12 weeks before last frost — germination requires warm soil (75–80°F) and darkness. Do not cover seeds deeply; they need just a light dusting. Direct sowing is rarely practiced due to slow seedling establishment. Transplant after soil warms and frost danger has passed. Excellent drought tolerance once established; avoid overwatering. Performs best in well-drained beds or containers in full sun.
Companion Planting
Good Companions
Check more plant combinations with our Companion Planting Checker →
Vinca (Annual) in Other Locations
Frequently Asked Questions
When should I plant Vinca (Annual) in Shelby County, TX?
Shelby County is in Zone 8b with an average last frost of March 6. Plan your Vinca (Annual) planting based on this frost date — see the calendar above for exact timing.
What planting zone is Shelby County, TX?
Shelby County, Texas is in USDA Hardiness Zone 8b. The average last spring frost is March 6 and first fall frost is November 16.
Your Shelby County Garden Planner — Free
A 22-page printable planner built for Shelby County (Zone 8b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.