When to plant Vinca (Annual) in Sullivan County, IN
In Sullivan County, Vinca (Annual) is a single-season spring crop — there's no second fall window. Plant April 25–May 9 for an 70–90-day harvest, finishing well before the October 17 first frost.
When to Plant Vinca (Annual) in Sullivan County, IN
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.
Sullivan County, Indiana is in USDA Zone 6b. The average last spring frost is April 18 and the first fall frost is October 17, giving you a growing season of approximately 182 days.
At an elevation of 914 feet, Sullivan County receives approximately 34.6 inches of rainfall annually with predominantly silt loam soil. Summer highs average 90°F, providing good warmth for Vinca (Annual) during the growing season.
Sullivan County Soil Profile
Soil Type
Silt Loam
Soil pH
6.0-7.0
Drainage
Well Drained
Vinca (Annual) Planting Timeline — Sullivan County, IN
Vinca (Annual) Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | February 7 | Feb 7 – Feb 21 |
| Transplant Outdoors | April 25 | Apr 25 – May 9 |
| Bloom | July 4 | Jul 4 – Oct 17 |
Plant 0.1" deep · 10" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | Start Indoors |
| March | — |
| April | Transplant Outdoors |
| May | Transplant Outdoors |
| June | — |
| July | Bloom |
| August | Bloom |
| September | Bloom |
| October | Bloom |
| November | — |
| 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 6b
📆 Growing Season
182 days in Sullivan County
Growing Tips for Sullivan 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 Sullivan County, IN?
Sullivan County is in Zone 6b with an average last frost of April 18. Plan your Vinca (Annual) planting based on this frost date — see the calendar above for exact timing.
What planting zone is Sullivan County, IN?
Sullivan County, Indiana is in USDA Hardiness Zone 6b. The average last spring frost is April 18 and first fall frost is October 17.
When should I plant Vinca (Annual) in Sullivan County, IN?
In Sullivan County, IN, plant Vinca (Annual) after the last frost (around April 18) and before the first frost (around October 17). Best results when soil holds above 50°F.
What growing zone is Sullivan County, IN for Vinca (Annual)?
Sullivan County sits in USDA Zone 6b. Vinca (Annual) grows reliably in zones 3a through 11b, so it's a good fit here.
Can Vinca (Annual) grow in Sullivan County's climate?
Yes — Vinca (Annual) grows well in Sullivan County's temperate climate. Sullivan County averages a 182-day frost-free season, with last frost around April 18 and first frost around October 17.
Your Sullivan County Garden Planner — Free
A 22-page printable planner built for Sullivan County (Zone 6b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.