When to Plant Sunflower in Oneida County, WI
Sunflowers are tall, cheerful annuals grown for their edible seeds and as pollinator magnets. They come in sizes from 2-foot dwarfs to 12-foot giants.
Oneida County, Wisconsin is in USDA Zone 4a. The average last spring frost is May 20 and the first fall frost is September 28, giving you a growing season of approximately 131 days.
At an elevation of 569 feet, Oneida County receives approximately 39.8 inches of rainfall annually with predominantly silt loam soil. Summer highs average 82°F, so choose short-season varieties of Sunflower to ensure they mature before fall.
Oneida County Soil Profile
Soil Type
Silt Loam
Soil pH
6.3-7.1
Drainage
Well Drained
Plant 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 Oneida County
How your county's soil matches Sunflower's growing requirements.
Soil pH
Your soil pH (6.3–7.1) is within Sunflower's preferred range (6.0–7.5).
Soil Texture
The silt loam soil in Oneida County is excellent for Sunflower — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (4.3%) — Sunflower will thrive.
How to Plant Sunflower
Succession Planting Sunflower
Sow every 8 weeks. Last sowing by Jun 20 to harvest before frost.
Plant Water Budget
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 | — | 1.9" | 0" | ❄️ Dormant |
| Feb | — | 1.6" | 0" | ❄️ Dormant |
| Mar | — | 2.7" | 0" | ❄️ Dormant |
| Apr | — | 4.2" | 0" | ❄️ Dormant |
| May | 2.2" | 4.9" | 0" | ✅ Rainfall sufficient |
| Jun | 2.2" | 4.6" | 0" | ✅ Rainfall sufficient |
| Jul | 2.2" | 4.4" | 0" | ✅ Rainfall sufficient |
| Aug | 2.2" | 3.9" | 0" | ✅ Rainfall sufficient |
| Sep | 2.2" | 3.5" | 0" | ✅ Rainfall sufficient |
| Oct | — | 3.3" | 0" | ❄️ Dormant |
| Nov | — | 2.5" | 0" | ❄️ Dormant |
| Dec | — | 2.3" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Sep in Oneida 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 — Oneida County, WI
Sunflower Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 18 | Mar 18 – Apr 1 |
| Transplant Outdoors | June 10 | Jun 10 – Jun 24 |
| Direct Sow | June 3 | Jun 3 – Jun 24 |
| Harvest | August 19 | Aug 19 – Oct 7 |
Plant 1" deep · 18" apart · Rows 30" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Start Indoors |
| May | — |
| June | Transplant Outdoors Direct Sow |
| July | — |
| August | Harvest |
| September | Harvest |
| October | Harvest |
| 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: ideal
🗺️ USDA Zone
Zone 4a
📆 Growing Season
131 days in Oneida County
Growing Tips for Sunflower in Oneida County
Direct sow Sunflower outdoors after May 20 in Oneida County when soil has warmed and frost danger has passed.
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 after last frost. Stake tall varieties in windy areas. Harvest seed heads when the back turns brown and seeds are plump. Dry heads upside down.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Sunflower in Other Locations
Frequently Asked Questions
When should I plant Sunflower in Oneida County, WI?
Oneida County is in Zone 4a with an average last frost of May 20. Plan your Sunflower planting based on this frost date — see the calendar above for exact timing.
What planting zone is Oneida County, WI?
Oneida County, Wisconsin is in USDA Hardiness Zone 4a. The average last spring frost is May 20 and first fall frost is September 28.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Oneida County gardeners in Zone 4a organize planting dates, track what's growing, and never miss a planting window.
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