When to plant Sunflower in Cole County, MO
For Sunflower in Cole County, the safe spring window opens around April 7 and closes around April 28. Last expected frost is April 7, first fall frost October 28, giving a 204-day growing season.
When to Plant Sunflower in Cole County, MO
Cole County, Missouri gardeners: here's your June plan
Here's what deserves your attention in Cole County, Missouri this month. Everything below is tailored to Zone 6b and timed around your local frost dates.
-
Pick sunflower
Don't tug. Use scissors or pruners for clean cuts — torn stems invite disease.
Looking ahead to 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.
Cole County, Missouri is in USDA Zone 6b. The average last spring frost is April 7 and the first fall frost is October 28, giving you a growing season of approximately 204 days.
At an elevation of 614 feet, Cole County receives approximately 39.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 88°F, providing good warmth for Sunflower during the growing season.
Cole County Soil Profile
Soil Type
Silt Loam
Soil pH
5.4-6.9
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 Cole County
How your county's soil matches Sunflower's growing requirements.
Soil pH
Your soil pH (5.4–6.9) overlaps with Sunflower's range (6.0–7.5), though not a perfect match.
Soil Texture
The silt loam soil in Cole County is excellent for Sunflower — good drainage, moisture retention, and nutrient holding capacity.
Drainage
Sunflower prefers dry conditions but your soil drains poorly. Use raised beds or mounded rows to prevent root rot.
Organic Matter
Organic matter is moderate (3.1%). Annual compost additions will help Sunflower.
How to Plant Sunflower
Succession Planting Sunflower
Sow every 8 weeks. Last sowing by Jul 20 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 | — | 1.6" | 0" | ❄️ Dormant |
| Feb | — | 1.5" | 0" | ❄️ Dormant |
| Mar | — | 2.4" | 0" | ❄️ Dormant |
| Apr | 2.2" | 4.4" | 0" | ✅ Rainfall sufficient |
| May | 2.2" | 4.6" | 0" | ✅ Rainfall sufficient |
| Jun | 2.2" | 5.5" | 0" | ✅ Rainfall sufficient |
| Jul | 2.2" | 4.2" | 0" | ✅ Rainfall sufficient |
| Aug | 2.2" | 4.1" | 0" | ✅ Rainfall sufficient |
| Sep | 2.2" | 3.6" | 0" | ✅ Rainfall sufficient |
| Oct | 2.2" | 2.8" | 0" | ✅ Rainfall sufficient |
| Nov | — | 2.6" | 0" | ❄️ Dormant |
| Dec | — | 1.9" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Cole 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 — Cole County, MO
Sunflower Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 17 | Mar 17 – Mar 31 |
| Transplant Outdoors | April 7 | Apr 7 – Apr 21 |
| Direct Sow | April 7 | Apr 7 – Apr 28 |
| Bloom | June 30 | Jun 30 – Sep 29 |
Plant 1" deep · 18" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Transplant Outdoors Direct Sow |
| May | — |
| 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: acceptable
🗺️ USDA Zone
Zone 6b
📆 Growing Season
204 days in Cole County
Growing Tips for Sunflower in Cole County
Direct sow Sunflower outdoors after April 07 in Cole 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 Cole County, MO?
Cole County is in Zone 6b with an average last frost of April 7. Plan your Sunflower planting based on this frost date — see the calendar above for exact timing.
What planting zone is Cole County, MO?
Cole County, Missouri is in USDA Hardiness Zone 6b. The average last spring frost is April 7 and first fall frost is October 28.
When should I plant Sunflower in Cole County, MO?
In Cole County, MO, plant Sunflower after the last frost (around April 7) and before the first frost (around October 28). Best results when soil holds above 50°F.
What growing zone is Cole County, MO for Sunflower?
Cole County sits in USDA Zone 6b. Sunflower grows reliably in zones 2a through 11b, so it's a good fit here.
Can Sunflower grow in Cole County's climate?
Yes — Sunflower grows well in Cole County's temperate climate. Cole County averages a 204-day frost-free season, with last frost around April 7 and first frost around October 28.
Your Cole County Garden Planner — Free
A 22-page printable planner built for Cole 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.