State × crop calendar
Sunflowers planting in Colorado.
- Primary crop
- Zone 5b
- 145-day season
- Last frost May 10
- Row Crop
- Semi-Hardy
Sunflowers planting in Colorado is shaped by the state's 5b dominant hardiness zone, last frost date around May 10, and a 145-day growing season. Sunflowers is widely grown in Colorado — commercially significant or common in home gardens and food plots.
Planting dates on this page are climatological estimates from USDA frost-date norms and zone-typical planting offsets. Verify against Colorado State University Extension for variety- and county-specific guidance.
Planting calendar — 2026
Frost-anchored windows.
Sunflowers · Colorado · planting calendar
Planting windows shift earlier in southern parts of the state and later in northern parts. Use last frost date in your specific county as the reference.
Planting windows
Earliest → ideal → latest.
Spring planting
SunflowersEarliest
May 3
Ideal start
May 17
Ideal end
June 14
Latest
July 5
Soil-temp trigger
Wait for 50°F minimum soil temp. Sunflowers tolerate light frost in seedling stage but not after stem elongation.Harvest window
Typical start
August 15
Typical end
September 14
Harvest timing varies with planting date and seasonal weather — these dates are typical for the ideal planting window.
Growing notes
Sunflowers grows well in Colorado's typical climate. Colorado's 145-day growing season and 5b hardiness zone support reliable production with appropriate variety selection.
Sunflowers is widely grown in Colorado — commercially significant or common in home gardens and food plots.
Agronomy reference
Sunflowers fundamentals.
Soil-temp minimum
50°F
Soil-temp optimum
55–80°F
Days to maturity
90–120
Water (in/wk)
0.5–1"
Soil pH
6–7.5
Nitrogen demand
moderate
Growing-degree-day requirement: 2000 GDD (base 44°F) from planting to maturity.
Oil-type sunflowers grown for crushing; confection-type for human consumption. Both work as dove fields — confection for larger seeds.
Common pests to watch
- Sunflower head moth
- Banded sunflower moth
- Birds (during head fill)
Pest pressure varies by region and year. Confirm current outbreaks with Colorado State University Extension.
Common diseases
- Sclerotinia head rot
- Phomopsis
- Rust
Resistance varieties shift each year. Check the current variety trial report for your state.
Variety selection
Sunflowers varieties for Colorado live with your extension.
Variety selection
Variety performance is micro-regional and changes with each year's trial cycle. We don't republish variety lists — instead, we point directly at the source.
Colorado State University Extension →Search the extension site for “sunflowers variety trial” or “recommended sunflowers varieties” to find the current report.
Yield varies significantly by variety, soil, fertility, and management. Consult your state extension service for variety performance trials in your region.
Sunflowers timing. Live alerts.
Bield: Farm ties weather and soil-temperature stations in your county to crop planting thresholds — get notified the day soil temp clears your target window.
Start free trial →