When to plant Vinca (Annual) in Hamilton County, IA
Hamilton County's 159-day season only supports one Vinca (Annual) planting per year. Sow between May 15 and May 29 for the best chance at full maturity before October 7.
When to Plant Vinca (Annual) in Hamilton County, IA
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.
Hamilton County, Iowa is in USDA Zone 5a. The average last spring frost is May 1 and the first fall frost is October 7, giving you a growing season of approximately 159 days.
At an elevation of 1,210 feet, Hamilton County receives approximately 35.8 inches of rainfall annually with predominantly silt loam soil. Summer highs average 80°F, so choose short-season varieties of Vinca (Annual) to ensure they mature before fall.
Hamilton County Soil Profile
Soil Type
Silt Loam
Soil pH
6.0-7.0
Drainage
Well Drained
Vinca (Annual) Planting Timeline — Hamilton County, IA
Vinca (Annual) Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | February 13 | Feb 13 – Feb 27 |
| Transplant Outdoors | May 15 | May 15 – May 29 |
| Bloom | July 24 | Jul 24 – Oct 9 |
Plant 0.1" deep · 10" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | Start Indoors |
| March | — |
| April | — |
| 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 5a
📆 Growing Season
159 days in Hamilton County
Growing Tips for Hamilton 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 Hamilton County, IA?
Hamilton County is in Zone 5a with an average last frost of May 1. Plan your Vinca (Annual) planting based on this frost date — see the calendar above for exact timing.
What planting zone is Hamilton County, IA?
Hamilton County, Iowa is in USDA Hardiness Zone 5a. The average last spring frost is May 1 and first fall frost is October 7.
When should I plant Vinca (Annual) in Hamilton County, IA?
In Hamilton County, IA, plant Vinca (Annual) after the last frost (around May 1) and before the first frost (around October 7). Best results when soil holds above 50°F.
What growing zone is Hamilton County, IA for Vinca (Annual)?
Hamilton 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 Hamilton County's climate?
Yes — Vinca (Annual) grows well in Hamilton County's temperate climate. Hamilton County averages a 159-day frost-free season, with last frost around May 1 and first frost around October 7.
Your Hamilton County Garden Planner — Free
A 22-page printable planner built for Hamilton 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.