When to Plant Vinca (Annual) in Uinta County, WY
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.
Uinta County, Wyoming is in USDA Zone 5a. The average last spring frost is June 17 and the first fall frost is August 31, giving you a growing season of approximately 75 days.
At an elevation of 5,768 feet, Uinta County receives approximately 23.5 inches of rainfall annually with predominantly loam soil. Summer highs average 82°F, so choose short-season varieties of Vinca (Annual) to ensure they mature before fall.
Uinta County Soil Profile
Soil Type
Loam
Soil pH
6.3-8.3
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 | — | 1.5" | 0" | ❄️ Dormant |
| Feb | — | 1.3" | 0" | ❄️ Dormant |
| Mar | — | 2.2" | 0" | ❄️ Dormant |
| Apr | — | 2.8" | 0" | ❄️ Dormant |
| May | — | 2.7" | 0" | ❄️ Dormant |
| Jun | 4.3" | 1.8" | 2.5" | 🚿 Regular watering |
| Jul | 4.3" | 1.8" | 2.5" | 🚿 Regular watering |
| Aug | 4.3" | 2.2" | 2.1" | 💧 Light watering |
| Sep | — | 2.2" | 0" | ❄️ Dormant |
| Oct | — | 1.9" | 0" | ❄️ Dormant |
| Nov | — | 1.7" | 0" | ❄️ Dormant |
| Dec | — | 1.5" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Jun–Aug in Uinta County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Vinca (Annual) Planting Timeline — Uinta County, WY
Vinca (Annual) Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | April 1 | Apr 1 – Apr 15 |
| Transplant Outdoors | July 1 | Jul 1 – Jul 15 |
| Bloom | September 9 | Sep 9 – Nov 25 |
Plant 0.1" deep · 10" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | Start Indoors |
| May | — |
| June | — |
| July | Transplant Outdoors |
| August | — |
| September | Bloom |
| October | Bloom |
| November | Bloom |
| December | — |
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 5a
📆 Growing Season
75 days in Uinta County
Growing Tips for Uinta 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 Uinta County, WY?
Uinta County is in Zone 5a with an average last frost of June 17. Plan your Vinca (Annual) planting based on this frost date — see the calendar above for exact timing.
What planting zone is Uinta County, WY?
Uinta County, Wyoming is in USDA Hardiness Zone 5a. The average last spring frost is June 17 and first fall frost is August 31.
Your Uinta County Garden Planner — Free
A 22-page printable planner built for Uinta County (Zone 5a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.