When to plant Vinca (Annual) in Madison County, ID
In Madison County, Vinca (Annual) is a single-season spring crop — there's no second fall window. Plant June 14–June 28 for an 70–90-day harvest, finishing well before the September 11 first frost.
When to Plant Vinca (Annual) in Madison 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.
Madison County, Idaho is in USDA Zone 5a. The average last spring frost is May 31 and the first fall frost is September 11, giving you a growing season of approximately 103 days.
At an elevation of 6,385 feet, Madison County receives approximately 19 inches of rainfall annually with predominantly loam soil. Summer highs average 85°F, providing good warmth for Vinca (Annual) during the growing season. With low rainfall, drip irrigation is essential for growing Vinca (Annual) successfully. Mulch heavily to conserve soil moisture.
Madison County Soil Profile
Soil Type
Loam
Soil pH
6.0-7.0
Drainage
Well Drained
Vinca (Annual) Planting Timeline — Madison County, ID
Vinca (Annual) Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 15 | Mar 15 – Mar 29 |
| Transplant Outdoors | June 14 | Jun 14 – Jun 28 |
| Bloom | August 23 | Aug 23 – Nov 8 |
Plant 0.1" deep · 10" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | — |
| May | — |
| June | Transplant Outdoors |
| July | — |
| August | Bloom |
| 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
103 days in Madison County
Growing Tips for Madison 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 Madison County, ID?
Madison County is in Zone 5a with an average last frost of May 31. Plan your Vinca (Annual) planting based on this frost date — see the calendar above for exact timing.
What planting zone is Madison County, ID?
Madison County, Idaho is in USDA Hardiness Zone 5a. The average last spring frost is May 31 and first fall frost is September 11.
When should I plant Vinca (Annual) in Madison County, ID?
In Madison County, ID, plant Vinca (Annual) after the last frost (around May 31) and before the first frost (around September 11). Best results when soil holds above 50°F.
What growing zone is Madison County, ID for Vinca (Annual)?
Madison 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 Madison County's climate?
Yes — Vinca (Annual) grows well in Madison County's temperate climate. Madison County averages a 103-day frost-free season, with last frost around May 31 and first frost around September 11.
Your Madison County Garden Planner — Free
A 22-page printable planner built for Madison 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.