When to Plant Vinca (Annual) in Cotton County, OK
What to do in June
We've pulled the most time-sensitive tasks for Cotton County, Oklahoma this June and put them front and centre. Tackle them in order.
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Sow vinca (annual) in trays indoors
Label every cell. You will absolutely forget which is which otherwise.
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It's harvest week for vinca (annual)
The more you pick, the more the plant produces. Letting fruit overripen tells the plant it's time to stop.
A few tasks this June that'll pay off in July
- 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.
Cotton County, Oklahoma is in USDA Zone 8a. The average last spring frost is March 25 and the first fall frost is November 10, giving you a growing season of approximately 230 days.
At an elevation of 1,015 feet, Cotton County receives approximately 20.6 inches of rainfall annually with predominantly loam soil. Summer highs average 92°F, providing good warmth for Vinca (Annual) during the growing season.
Cotton County Soil Profile
Soil Type
Loam
Soil pH
6.3-7.5
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 Cotton County
How your county's soil matches Vinca (Annual)'s growing requirements.
Soil pH
Your soil pH (6.3–7.5) overlaps with Vinca (Annual)'s range (6.0–7.0), though not a perfect match.
Soil Texture
The loam soil in Cotton County is excellent for Vinca (Annual) — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (3.8%). Annual compost additions will help Vinca (Annual).
How to Plant Vinca (Annual)
Succession Planting Vinca (Annual)
Sow every 8 weeks. Last sowing by Aug 12 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 | — | 0.5" | 0" | ❄️ Dormant |
| Feb | — | 0.8" | 0" | ❄️ Dormant |
| Mar | 2.2" | 1.4" | 0.8" | 💧 Light watering |
| Apr | 2.2" | 2.2" | 0" | ✅ Rainfall sufficient |
| May | 2.2" | 2.7" | 0" | ✅ Rainfall sufficient |
| Jun | 2.2" | 2.9" | 0" | ✅ Rainfall sufficient |
| Jul | 2.2" | 2.9" | 0" | ✅ Rainfall sufficient |
| Aug | 2.2" | 2.6" | 0" | ✅ Rainfall sufficient |
| Sep | 2.2" | 1.9" | 0.3" | 💧 Light watering |
| Oct | 2.2" | 1.5" | 0.7" | 💧 Light watering |
| Nov | 2.2" | 0.8" | 1.4" | 🚿 Regular watering |
| Dec | — | 0.5" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Mar–Nov in Cotton 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 — Cotton County, OK
Vinca (Annual) Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | January 14 | Jan 14 – Jan 28 |
| Transplant Outdoors | March 18 | Mar 18 – Apr 1 |
| Bloom | May 27 | May 27 – Oct 14 |
Plant 0.1" deep · 10" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | Start Indoors |
| February | — |
| March | Transplant Outdoors |
| April | Transplant Outdoors |
| May | Bloom |
| June | Bloom |
| July | Bloom |
| August | Bloom |
| September | Bloom |
| October | Bloom |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
0.5"/week · Only during dry spells
📅 Days to Maturity
70–90 days
🧪 Soil pH
Needs 6–7 · Your soil: acceptable
🗺️ USDA Zone
Zone 8a
📆 Growing Season
230 days in Cotton County
Growing Tips for Vinca (Annual) in Cotton County
Direct sow Vinca (Annual) outdoors after March 25 in Cotton County when soil has warmed and frost danger has passed.
Cotton County receives only 21" of rain annually. Vinca (Annual) needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.
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 Cotton County, OK?
Cotton County is in Zone 8a with an average last frost of March 25. Plan your Vinca (Annual) planting based on this frost date — see the calendar above for exact timing.
What planting zone is Cotton County, OK?
Cotton County, Oklahoma is in USDA Hardiness Zone 8a. The average last spring frost is March 25 and first fall frost is November 10.
Your Cotton County Garden Planner — Free
A 22-page printable planner built for Cotton County (Zone 8a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.