When to Plant Vinca (Annual) in Klamath County, OR
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.
Klamath County, Oregon is in USDA Zone 6b. The average last spring frost is June 13 and the first fall frost is September 21, giving you a growing season of approximately 100 days.
At an elevation of 142 feet, Klamath County receives approximately 48.7 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83°F, so choose short-season varieties of Vinca (Annual) to ensure they mature before fall.
Klamath County Soil Profile
Soil Type
Silt Loam
Soil pH
5.5-6.3
Drainage
Well Drained
Monthly Watering Guide for Vinca (Annual)
Vinca (Annual) needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.
| Month | Vinca (Annual) Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 7.4" | 0" | ❄️ Dormant |
| Feb | — | 5.2" | 0" | ❄️ Dormant |
| Mar | — | 4.8" | 0" | ❄️ Dormant |
| Apr | — | 3.3" | 0" | ❄️ Dormant |
| May | — | 3" | 0" | ❄️ Dormant |
| Jun | 4.3" | 1.8" | 2.5" | 🚿 Regular watering |
| Jul | 4.3" | 0.9" | 3.4" | 🚿 Regular watering |
| Aug | 4.3" | 0.8" | 3.5" | 🚿 Regular watering |
| Sep | 4.3" | 2.1" | 2.2" | 🚿 Regular watering |
| Oct | — | 4.8" | 0" | ❄️ Dormant |
| Nov | — | 7.7" | 0" | ❄️ Dormant |
| Dec | — | 6.9" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Jun–Sep in Klamath County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Vinca (Annual) Planting Timeline — Klamath County, OR
Vinca (Annual) Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | April 4 | Apr 4 – Apr 18 |
| Transplant Outdoors | June 20 | Jun 20 – Jul 4 |
| Bloom | August 29 | Aug 29 – Dec 12 |
Plant 0.1" deep · 10" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | Start Indoors |
| May | — |
| June | Transplant Outdoors |
| July | Transplant Outdoors |
| August | Bloom |
| September | Bloom |
| October | Bloom |
| November | Bloom |
| December | Bloom |
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
100 days in Klamath County
Growing Tips for Klamath 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 Klamath County, OR?
Klamath County is in Zone 6b with an average last frost of June 13. Plan your Vinca (Annual) planting based on this frost date — see the calendar above for exact timing.
What planting zone is Klamath County, OR?
Klamath County, Oregon is in USDA Hardiness Zone 6b. The average last spring frost is June 13 and first fall frost is September 21.
Your Klamath County Garden Planner — Free
A 22-page printable planner built for Klamath 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.