When to plant Vinca (Annual) in Massac County, IL
In Massac County, Vinca (Annual) is a single-season spring crop — there's no second fall window. Plant April 7–April 21 for an 70–90-day harvest, finishing well before the October 21 first frost.
When to Plant Vinca (Annual) in Massac County, IL
Your August planting checklist for Massac County, Illinois
August rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Massac County, Illinois.
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Harvest vinca (annual) as they ripen
If you can't use it all right away, check the food-preservation section of your planner.
September prep starts now
- First harvests: vinca (annual)
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.
Massac County, Illinois is in USDA Zone 7a. The average last spring frost is April 7 and the first fall frost is October 21, giving you a growing season of approximately 197 days.
At an elevation of 778 feet, Massac County receives approximately 36 inches of rainfall annually with predominantly silt loam soil. Summer highs average 86°F, providing good warmth for Vinca (Annual) during the growing season.
Massac County Soil Profile
Soil Type
Silt Loam
Soil pH
5.8-7
Drainage
Well Drained
Vinca (Annual) Planting Risk Windows
Percentages indicate frost risk at transplant. The 70% safe window means there is a 30% chance of frost after transplant — suitable for cold-hardy crops or gardeners with frost protection. The 90% safe window is best for tender plants.
Soil Compatibility in Massac County
How your county's soil matches Vinca (Annual)'s growing requirements.
Soil pH
Your soil pH (5.8–7.0) overlaps with Vinca (Annual)'s range (6.0–7.0), though not a perfect match.
Soil Texture
The silt loam soil in Massac County is excellent for Vinca (Annual) — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (4.7%) — Vinca (Annual) will thrive.
How to Plant Vinca (Annual)
Succession Planting Vinca (Annual)
Sow every 8 weeks. Last sowing by Jul 23 to harvest before frost.
Vinca (Annual) Water Budget
Monthly Watering Guide for Vinca (Annual)
Vinca (Annual) needs approximately 0.5 inches of water per week (2.2" per month). Here's how your county's rainfall compares month by month.
| Month | Vinca (Annual) Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1.3" | 0" | ❄️ Dormant |
| Feb | — | 1.8" | 0" | ❄️ Dormant |
| Mar | — | 2.5" | 0" | ❄️ Dormant |
| Apr | 2.2" | 3.6" | 0" | ✅ Rainfall sufficient |
| May | 2.2" | 3.6" | 0" | ✅ Rainfall sufficient |
| Jun | 2.2" | 4.8" | 0" | ✅ Rainfall sufficient |
| Jul | 2.2" | 3.7" | 0" | ✅ Rainfall sufficient |
| Aug | 2.2" | 3.6" | 0" | ✅ Rainfall sufficient |
| Sep | 2.2" | 3.4" | 0" | ✅ Rainfall sufficient |
| Oct | 2.2" | 3.1" | 0" | ✅ Rainfall sufficient |
| Nov | — | 2.6" | 0" | ❄️ Dormant |
| Dec | — | 2.1" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Massac County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Vinca (Annual) Heat Requirements (GDD)
What are Growing Degree Days (GDD)?
Growing Degree Days measure the total warmth your plants receive during the growing season. Think of it as a "heat bank" — every day above 50°F deposits warmth that helps your plants grow.
Each plant needs a certain amount of accumulated heat to mature. If your county provides more GDD than the plant needs, it's a great fit. If it's close, you may want to choose faster-maturing varieties or start seeds indoors to get a head start.
Vinca (Annual) Planting Timeline — Massac County, IL
Vinca (Annual) Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | January 27 | Jan 27 – Feb 10 |
| Transplant Outdoors | April 7 | Apr 7 – Apr 21 |
| Bloom | June 16 | Jun 16 – Oct 6 |
Plant 0.1" deep · 10" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | Start Indoors |
| February | Start Indoors |
| March | — |
| April | Transplant Outdoors |
| May | — |
| June | Bloom |
| July | Bloom |
| August | Bloom |
| September | Bloom |
| October | Bloom |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
0.5"/week · Natural rainfall sufficient
📅 Days to Maturity
70–90 days
🧪 Soil pH
Needs 6–7 · Your soil: acceptable
🗺️ USDA Zone
Zone 7a
📆 Growing Season
197 days in Massac County
Growing Tips for Vinca (Annual) in Massac County
Direct sow Vinca (Annual) outdoors after April 07 in Massac County when soil has warmed and frost danger has passed.
General growing tips
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 Massac County, IL?
Massac County is in Zone 7a with an average last frost of April 7. Plan your Vinca (Annual) planting based on this frost date — see the calendar above for exact timing.
What planting zone is Massac County, IL?
Massac County, Illinois is in USDA Hardiness Zone 7a. The average last spring frost is April 7 and first fall frost is October 21.
When should I plant Vinca (Annual) in Massac County, IL?
In Massac County, IL, plant Vinca (Annual) after the last frost (around April 7) and before the first frost (around October 21). Best results when soil holds above 50°F.
What growing zone is Massac County, IL for Vinca (Annual)?
Massac County sits in USDA Zone 7a. Vinca (Annual) grows reliably in zones 3a through 11b, so it's a good fit here.
Can Vinca (Annual) grow in Massac County's climate?
Yes — Vinca (Annual) grows well in Massac County's temperate climate. Massac County averages a 197-day frost-free season, with last frost around April 7 and first frost around October 21.
Your Massac County Garden Planner — Free
A 22-page printable planner built for Massac County (Zone 7a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.