When to plant Vinca (Annual) in St. Johns County, FL
Plant Vinca (Annual) in St. Johns County, between January 12 and January 26 — the only viable window. Zone 9b's short season (297 frost-free days) rules out a fall crop.
When to Plant Vinca (Annual) in St. Johns County, FL
What to do in August
Here's what deserves your attention in St. Johns County, Florida this month. Everything below is tailored to Zone 9b and timed around your local frost dates.
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Start harvesting vinca (annual)
Taste as you pick. The first ripe produce is the best feedback loop you'll get all season.
Looking ahead to September
- 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.
St. Johns County, Florida is in USDA Zone 9b. The average last spring frost is February 9 and the first fall frost is December 2, giving you a growing season of approximately 296 days.
At an elevation of 57 feet, St. Johns County receives approximately 51.1 inches of rainfall annually with predominantly sand soil. Summer highs average 99°F, so Vinca (Annual) may need afternoon shade and extra watering during peak heat. Sandy soil warms quickly in spring — great for early planting — but Vinca (Annual) will need more frequent watering and organic matter to retain nutrients. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Vinca (Annual) root diseases.
St. Johns County Soil Profile
Soil Type
Sand
Soil pH
4.9-6.1
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 St. Johns County
How your county's soil matches Vinca (Annual)'s growing requirements.
Soil pH
Your soil pH (4.9–6.1) is more acidic than Vinca (Annual) prefers (6.0–7.0). Add garden lime to raise pH.
Soil Texture
Sandy soil in St. Johns County warms quickly in spring but drains fast. Vinca (Annual) will need more frequent watering and regular compost additions to retain nutrients.
Organic Matter
Organic matter is low (1.5%). Add 2-3 inches of compost before planting Vinca (Annual).
How to Plant Vinca (Annual)
Succession Planting Vinca (Annual)
Sow every 8 weeks. Last sowing by Sep 03 to harvest before frost.
Vinca (Annual) Water Budget
Water stress score is 6/10 — 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 | — | 2.4" | 0" | ❄️ Dormant |
| Feb | 2.2" | 2.4" | 0" | ✅ Rainfall sufficient |
| Mar | 2.2" | 2.8" | 0" | ✅ Rainfall sufficient |
| Apr | 2.2" | 2.8" | 0" | ✅ Rainfall sufficient |
| May | 2.2" | 3.5" | 0" | ✅ Rainfall sufficient |
| Jun | 2.2" | 7" | 0" | ✅ Rainfall sufficient |
| Jul | 2.2" | 7.1" | 0" | ✅ Rainfall sufficient |
| Aug | 2.2" | 7.6" | 0" | ✅ Rainfall sufficient |
| Sep | 2.2" | 6.9" | 0" | ✅ Rainfall sufficient |
| Oct | 2.2" | 4.3" | 0" | ✅ Rainfall sufficient |
| Nov | 2.2" | 2.1" | 0.1" | 💧 Light watering |
| Dec | 2.2" | 2.3" | 0" | ✅ Rainfall sufficient |
Water needs are for active growing months only (Feb–Dec in St. Johns 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 — St. Johns County, FL
Vinca (Annual) Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | December 1 | Dec 1 – Dec 15 |
| Transplant Outdoors | January 12 | Jan 12 – Jan 26 |
| Bloom | March 23 | Mar 23 – Oct 5 |
Plant 0.1" deep · 10" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | Transplant Outdoors |
| February | — |
| March | Bloom |
| April | Bloom |
| May | Bloom |
| June | Bloom |
| July | Bloom |
| August | Bloom |
| September | Bloom |
| October | Bloom |
| November | — |
| December | Start Indoors |
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_acidic
🗺️ USDA Zone
Zone 9b
📆 Growing Season
296 days in St. Johns County
Growing Tips for Vinca (Annual) in St. Johns County
Direct sow Vinca (Annual) outdoors after February 09 in St. Johns County when soil has warmed and frost danger has passed.
Sandy soil in St. Johns County dries quickly — mulch Vinca (Annual) with 2-3 inches of straw and water deeply 2-3 times per week rather than lightly every day.
With summer highs reaching 99°F in St. Johns County, provide afternoon shade for Vinca (Annual) and water deeply in the morning.
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 St. Johns County, FL?
St. Johns County is in Zone 9b with an average last frost of February 9. Plan your Vinca (Annual) planting based on this frost date — see the calendar above for exact timing.
What planting zone is St. Johns County, FL?
St. Johns County, Florida is in USDA Hardiness Zone 9b. The average last spring frost is February 9 and first fall frost is December 2.
When should I plant Vinca (Annual) in St. Johns County, FL?
In St. Johns County, FL, plant Vinca (Annual) after the last frost (around February 9) and before the first frost (around December 2). Best results when soil holds above 50°F.
What growing zone is St. Johns County, FL for Vinca (Annual)?
St. Johns County sits in USDA Zone 9b. Vinca (Annual) grows reliably in zones 3a through 11b, so it's a good fit here.
Can Vinca (Annual) grow in St. Johns County's climate?
Yes — Vinca (Annual) grows well in St. Johns County's temperate climate. St. Johns County averages a 297-day frost-free season, with last frost around February 9 and first frost around December 2.
Your St. Johns County Garden Planner — Free
A 22-page printable planner built for St. Johns County (Zone 9b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.