When to plant Vinca (Annual) in Valley County, ID
Valley County's 77-day season only supports one Vinca (Annual) planting per year. Sow between July 2 and July 16 for the best chance at full maturity before September 3.
When to Plant Vinca (Annual) in Valley County, ID
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.
Valley County, Idaho is in USDA Zone 5a. The average last spring frost is June 18 and the first fall frost is September 3, giving you a growing season of approximately 77 days.
At an elevation of 7,884 feet, Valley County receives approximately 17.8 inches of rainfall annually with predominantly loam soil. Summer highs average 83°F, so choose short-season varieties of Vinca (Annual) to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Vinca (Annual) successfully. Mulch heavily to conserve soil moisture.
Valley County Soil Profile
Soil Type
Loam
Soil pH
6.4-8.4
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 | — | 1.2" | 0" | ❄️ Dormant |
| Feb | — | 1" | 0" | ❄️ Dormant |
| Mar | — | 1.7" | 0" | ❄️ Dormant |
| Apr | — | 2.2" | 0" | ❄️ Dormant |
| May | — | 2.1" | 0" | ❄️ Dormant |
| Jun | 4.3" | 1.1" | 3.2" | 🚿 Regular watering |
| Jul | 4.3" | 1.5" | 2.8" | 🚿 Regular watering |
| Aug | 4.3" | 1.9" | 2.4" | 🚿 Regular watering |
| Sep | 4.3" | 1.4" | 2.9" | 🚿 Regular watering |
| Oct | — | 1.5" | 0" | ❄️ Dormant |
| Nov | — | 1.4" | 0" | ❄️ Dormant |
| Dec | — | 0.9" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Jun–Sep in Valley County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Vinca (Annual) Planting Timeline — Valley County, ID
Vinca (Annual) Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | April 2 | Apr 2 – Apr 16 |
| Transplant Outdoors | July 2 | Jul 2 – Jul 16 |
| Bloom | September 10 | Sep 10 – Nov 26 |
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
77 days in Valley County
Growing Tips for Valley 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 Valley County, ID?
Valley County is in Zone 5a with an average last frost of June 18. Plan your Vinca (Annual) planting based on this frost date — see the calendar above for exact timing.
What planting zone is Valley County, ID?
Valley County, Idaho is in USDA Hardiness Zone 5a. The average last spring frost is June 18 and first fall frost is September 3.
When should I plant Vinca (Annual) in Valley County, ID?
In Valley County, ID, plant Vinca (Annual) after the last frost (around June 18) and before the first frost (around September 3). Best results when soil holds above 50°F.
What growing zone is Valley County, ID for Vinca (Annual)?
Valley County sits in USDA Zone 5a. Vinca (Annual) grows reliably in zones 3a through 11b, so it's a good fit here.
Can Vinca (Annual) grow in Valley County's climate?
Yes — Vinca (Annual) grows well in Valley County's temperate climate. Valley County averages a 77-day frost-free season, with last frost around June 18 and first frost around September 3.
Your Valley County Garden Planner — Free
A 22-page printable planner built for Valley 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.