When to plant Sunflower in Saint Augustine, FL
Spring Sunflower in Saint Augustine goes in January 12–February 2, once nighttime temps stop dipping near freezing.
When to Plant Sunflower in Saint Augustine, FL
Top priorities for St. Johns County, Florida gardeners in June
Your garden in St. Johns County, Florida is working on a schedule, even when you're not. Here's where you should be this June.
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Harvest sunflower as they ripen
This is the payoff month. Bring a basket, bring a friend, and get into the beds.
Get ahead of July
- First harvests: sunflower
Sunflower (Helianthus annuus) is a fast-growing North American native annual famous for its towering stems and brilliant yellow heads. It thrives in full sun and heat, producing large, pollen-rich blooms that attract bees, butterflies, and seed-eating birds. Varieties range from 18-inch dwarfs to 12-foot giants and nearly every color except blue.
Saint Augustine, 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 Sunflower may need afternoon shade and extra watering during peak heat. Sandy soil warms quickly in spring — great for early planting — but Sunflower will need more frequent watering and organic matter to retain nutrients. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Sunflower root diseases.
Saint Augustine Soil Profile
Soil Type
Sand
Soil pH
4.9-6.1
Drainage
Well Drained
Sunflower 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 Saint Augustine
How your county's soil matches Sunflower's growing requirements.
Soil pH
Your soil pH (4.9–6.1) is more acidic than Sunflower prefers (6.0–7.5). Add garden lime to raise pH.
Soil Texture
Sandy soil in St. Johns County warms quickly in spring but drains fast. Sunflower 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 Sunflower.
How to Plant Sunflower
Succession Planting Sunflower
Sow every 8 weeks. Last sowing by Aug 24 to harvest before frost.
Sunflower Water Budget
Water stress score is 6/10 — consider drought-tolerant varieties and mulching
Monthly Watering Guide for Sunflower
Sunflower 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 | Sunflower 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.
Sunflower 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.
Sunflower Planting Timeline — Saint Augustine, FL
Sunflower Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | January 19 | Jan 19 – Feb 2 |
| Transplant Outdoors | January 12 | Jan 12 – Jan 26 |
| Direct Sow | January 12 | Jan 12 – Feb 2 |
| Bloom | April 6 | Apr 6 – Sep 21 |
Plant 1" deep · 18" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | Start Indoors Transplant Outdoors Direct Sow |
| February | Start Indoors Direct Sow |
| March | — |
| April | Bloom |
| May | Bloom |
| June | Bloom |
| July | Bloom |
| August | Bloom |
| September | Bloom |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
0.5"/week · Natural rainfall sufficient
📅 Days to Maturity
70–100 days
🧪 Soil pH
Needs 6–7.5 · Your soil: too_acidic
🗺️ USDA Zone
Zone 9b
📆 Growing Season
296 days in St. Johns County
Growing Tips for Sunflower in Saint Augustine
Direct sow Sunflower 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 Sunflower 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 Sunflower and water deeply in the morning.
Common pests for Sunflower in this region include aphids and slugs. Use row covers early in the season and inspect plants weekly.
General growing tips
Direct-sow 1 inch deep after last frost; germination takes 7-14 days at 65-75°F soil. Sunflowers dislike root disturbance so direct sowing is strongly preferred over transplanting. Plant in succession every 2 weeks for extended bloom. Stake tall varieties. Avoid overwatering — they tolerate drought once established. Birds will self-deadhead seed heads; leave them up through fall for wildlife.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Sunflower in Other Locations
When should I plant Sunflower in Saint Augustine, FL?
In Saint Augustine, FL, plant Sunflower 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 Saint Augustine, FL for Sunflower?
Saint Augustine sits in USDA Zone 9b. Sunflower grows reliably in zones 2a through 11b, so it's a good fit here.
Can Sunflower grow in Saint Augustine's climate?
Yes — Sunflower grows well in Saint Augustine's temperate climate. Saint Augustine 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.