When to Plant Vinca (Annual) in Barron County, WI
Your June game plan for Barron County, Wisconsin
If you only do a handful of things in the garden this June, make it these. They're sequenced around your zone's frost timing.
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.
Barron County, Wisconsin is in USDA Zone 4b. The average last spring frost is May 17 and the first fall frost is September 25, giving you a growing season of approximately 131 days.
At an elevation of 1,256 feet, Barron County receives approximately 40.4 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.
Barron 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 Barron 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 Barron County is excellent for Vinca (Annual) — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (4.9%) — Vinca (Annual) will thrive.
How to Plant Vinca (Annual)
Succession Planting Vinca (Annual)
Sow every 8 weeks. Last sowing by Jun 27 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 | — | 1.6" | 0" | ❄️ Dormant |
| Feb | — | 1.6" | 0" | ❄️ Dormant |
| Mar | — | 2.8" | 0" | ❄️ Dormant |
| Apr | — | 4.3" | 0" | ❄️ Dormant |
| May | 2.2" | 4.6" | 0" | ✅ Rainfall sufficient |
| Jun | 2.2" | 5.6" | 0" | ✅ Rainfall sufficient |
| Jul | 2.2" | 3.9" | 0" | ✅ Rainfall sufficient |
| Aug | 2.2" | 4" | 0" | ✅ Rainfall sufficient |
| Sep | 2.2" | 3.3" | 0" | ✅ Rainfall sufficient |
| Oct | — | 3" | 0" | ❄️ Dormant |
| Nov | — | 3.2" | 0" | ❄️ Dormant |
| Dec | — | 2.5" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Sep in Barron 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 — Barron County, WI
Vinca (Annual) Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 1 | Mar 1 – Mar 15 |
| Transplant Outdoors | May 31 | May 31 – Jun 14 |
| Bloom | August 9 | Aug 9 – Oct 18 |
Plant 0.1" deep · 10" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | — |
| May | Transplant Outdoors |
| June | Transplant Outdoors |
| July | — |
| 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 4b
📆 Growing Season
131 days in Barron County
Growing Tips for Vinca (Annual) in Barron County
Direct sow Vinca (Annual) outdoors after May 17 in Barron 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 Barron County, WI?
Barron County is in Zone 4b with an average last frost of May 17. Plan your Vinca (Annual) planting based on this frost date — see the calendar above for exact timing.
What planting zone is Barron County, WI?
Barron County, Wisconsin is in USDA Hardiness Zone 4b. The average last spring frost is May 17 and first fall frost is September 25.
Your Barron County Garden Planner — Free
A 22-page printable planner built for Barron County (Zone 4b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.