When to plant Vinca (Annual) in Grant County, KS
Grant County sits in cold Zone 6b. Plant Vinca (Annual) April 28–May 12 for the single annual harvest; the October 17 first frost closes the window.
When to Plant Vinca (Annual) in Grant County, KS
What to do in August
Each item below is timed to Grant County, Kansas's frost dates and soil temperatures. Skip nothing, stress about nothing.
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Basket week: vinca (annual)
If you can't use it all right away, check the food-preservation section of your planner.
September will be here before you know it — start on
- 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.
Grant County, Kansas is in USDA Zone 6b. The average last spring frost is April 21 and the first fall frost is October 17, giving you a growing season of approximately 179 days.
At an elevation of 1,096 feet, Grant County receives approximately 25.2 inches of rainfall annually with predominantly loam soil. Summer highs average 85°F, providing good warmth for Vinca (Annual) during the growing season.
Grant County Soil Profile
Soil Type
Loam
Soil pH
6.4-7.7
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 Grant County
How your county's soil matches Vinca (Annual)'s growing requirements.
Soil pH
Your soil pH (6.4–7.7) is more alkaline than Vinca (Annual) prefers (6.0–7.0). Add sulfur or peat moss to lower pH.
Soil Texture
The loam soil in Grant County is excellent for Vinca (Annual) — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (4.1%) — Vinca (Annual) will thrive.
How to Plant Vinca (Annual)
Succession Planting Vinca (Annual)
Sow every 8 weeks. Last sowing by Jul 19 to harvest before frost.
Vinca (Annual) Water Budget
Water stress score is 8/10 — consider drought-tolerant varieties and mulching
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 | — | 1.8" | 0" | ❄️ Dormant |
| Feb | — | 1.5" | 0" | ❄️ Dormant |
| Mar | — | 2" | 0" | ❄️ Dormant |
| Apr | 2.2" | 3" | 0" | ✅ Rainfall sufficient |
| May | 2.2" | 2.8" | 0" | ✅ Rainfall sufficient |
| Jun | 2.2" | 1.9" | 0.3" | 💧 Light watering |
| Jul | 2.2" | 2" | 0.2" | 💧 Light watering |
| Aug | 2.2" | 2.7" | 0" | ✅ Rainfall sufficient |
| Sep | 2.2" | 2.4" | 0" | ✅ Rainfall sufficient |
| Oct | 2.2" | 2.1" | 0.1" | 💧 Light watering |
| Nov | — | 1.6" | 0" | ❄️ Dormant |
| Dec | — | 1.5" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Grant 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 — Grant County, KS
Vinca (Annual) Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | February 10 | Feb 10 – Feb 24 |
| Transplant Outdoors | April 28 | Apr 28 – May 12 |
| Bloom | July 7 | Jul 7 – Oct 20 |
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
0.5"/week · Natural rainfall sufficient
📅 Days to Maturity
70–90 days
🧪 Soil pH
Needs 6–7 · Your soil: too_alkaline
🗺️ USDA Zone
Zone 6b
📆 Growing Season
179 days in Grant County
Growing Tips for Vinca (Annual) in Grant County
Direct sow Vinca (Annual) outdoors after April 21 in Grant 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 Grant County, KS?
Grant County is in Zone 6b with an average last frost of April 21. Plan your Vinca (Annual) planting based on this frost date — see the calendar above for exact timing.
What planting zone is Grant County, KS?
Grant County, Kansas is in USDA Hardiness Zone 6b. The average last spring frost is April 21 and first fall frost is October 17.
When should I plant Vinca (Annual) in Grant County, KS?
In Grant County, KS, plant Vinca (Annual) after the last frost (around April 21) and before the first frost (around October 17). Best results when soil holds above 50°F.
What growing zone is Grant County, KS for Vinca (Annual)?
Grant 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 Grant County's climate?
Yes — Vinca (Annual) grows well in Grant County's temperate climate. Grant County averages a 179-day frost-free season, with last frost around April 21 and first frost around October 17.
Your Grant County Garden Planner — Free
A 22-page printable planner built for Grant 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.