When to Plant Sunflower in Ottawa County, OH
Your June planting checklist for Ottawa County, Ohio
Each item below is timed to Ottawa County, Ohio's frost dates and soil temperatures. Skip nothing, stress about nothing.
July will be here before you know it — start on
- 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.
Ottawa County, Ohio is in USDA Zone 6b. The average last spring frost is April 25 and the first fall frost is October 25, giving you a growing season of approximately 183 days.
At an elevation of 1,264 feet, Ottawa County receives approximately 31.1 inches of rainfall annually with predominantly silt loam soil. Summer highs average 88°F, providing good warmth for Sunflower during the growing season.
Ottawa County Soil Profile
Soil Type
Silt Loam
Soil pH
6.2-7
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 Ottawa County
How your county's soil matches Sunflower's growing requirements.
Soil pH
Your soil pH (6.2–7.0) is within Sunflower's preferred range (6.0–7.5).
Soil Texture
The silt loam soil in Ottawa County is excellent for Sunflower — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (5.1%) — Sunflower will thrive.
How to Plant Sunflower
Succession Planting Sunflower
Sow every 8 weeks. Last sowing by Jul 17 to harvest before frost.
Sunflower 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 | — | 1.4" | 0" | ❄️ Dormant |
| Feb | — | 1.3" | 0" | ❄️ Dormant |
| Mar | — | 1.9" | 0" | ❄️ Dormant |
| Apr | 2.2" | 3.2" | 0" | ✅ Rainfall sufficient |
| May | 2.2" | 3.9" | 0" | ✅ Rainfall sufficient |
| Jun | 2.2" | 3.9" | 0" | ✅ Rainfall sufficient |
| Jul | 2.2" | 3.3" | 0" | ✅ Rainfall sufficient |
| Aug | 2.2" | 2.9" | 0" | ✅ Rainfall sufficient |
| Sep | 2.2" | 3.1" | 0" | ✅ Rainfall sufficient |
| Oct | 2.2" | 2.2" | 0" | ✅ Rainfall sufficient |
| Nov | — | 2.2" | 0" | ❄️ Dormant |
| Dec | — | 1.6" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Ottawa 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 — Ottawa County, OH
Sunflower Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | April 4 | Apr 4 – Apr 18 |
| Transplant Outdoors | April 25 | Apr 25 – May 9 |
| Direct Sow | April 25 | Apr 25 – May 16 |
| Bloom | July 18 | Jul 18 – Oct 17 |
Plant 1" deep · 18" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | Start Indoors Transplant Outdoors Direct Sow |
| May | Transplant Outdoors Direct Sow |
| June | — |
| July | Bloom |
| 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
70–100 days
🧪 Soil pH
Needs 6–7.5 · Your soil: ideal
🗺️ USDA Zone
Zone 6b
📆 Growing Season
183 days in Ottawa County
Growing Tips for Sunflower in Ottawa County
Direct sow Sunflower outdoors after April 25 in Ottawa 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 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
Frequently Asked Questions
When should I plant Sunflower in Ottawa County, OH?
Ottawa County is in Zone 6b with an average last frost of April 25. Plan your Sunflower planting based on this frost date — see the calendar above for exact timing.
What planting zone is Ottawa County, OH?
Ottawa County, Ohio is in USDA Hardiness Zone 6b. The average last spring frost is April 25 and first fall frost is October 25.
Your Ottawa County Garden Planner — Free
A 22-page printable planner built for Ottawa 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.