When to Plant Sunflower in Cass County, MO
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.
Cass County, Missouri is in USDA Zone 6a. The average last spring frost is April 14 and the first fall frost is October 22, giving you a growing season of approximately 191 days.
At an elevation of 910 feet, Cass County receives approximately 37 inches of rainfall annually with predominantly silt loam soil. Summer highs average 87°F, providing good warmth for Sunflower during the growing season.
Cass County Soil Profile
Soil Type
Silt Loam
Soil pH
5.7-6.8
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.
Plant Water Budget
Sunflower Planting Timeline — Cass County, MO
Sunflower Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | February 17 | Feb 17 – Mar 3 |
| Transplant Outdoors | April 28 | Apr 28 – May 12 |
| Direct Sow | April 21 | Apr 21 – May 12 |
| Harvest | July 7 | Jul 7 – Aug 25 |
Plant 1" deep · 18" apart · Rows 30" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | Start Indoors |
| March | Start Indoors |
| April | Transplant Outdoors Direct Sow |
| May | Transplant Outdoors Direct Sow |
| June | — |
| July | Harvest |
| August | Harvest |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
Sun
Full Sun (6-8+ hours)
Water
Low — drought tolerant
Days to Maturity
70–100 days
Soil pH
6 – 7.5
USDA Zone
Zone 6a
Growing Season
191 days
Growing Tips for Cass County
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
Level Up Your Garden
Sunflower in Other Locations
Frequently Asked Questions
When should I plant Sunflower in Cass County, MO?
Cass County is in Zone 6a with an average last frost of April 14. Plan your Sunflower planting based on this frost date — see the calendar above for exact timing.
What planting zone is Cass County, MO?
Cass County, Missouri is in USDA Hardiness Zone 6a. The average last spring frost is April 14 and first fall frost is October 22.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Cass County gardeners in Zone 6a organize planting dates, track what's growing, and never miss a planting window.
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