Growing sunflower in zone 9a
(Zone 9a = an average winter low of 20°F to 25°F.)
In USDA zone 9a, the typical last spring frost is March 2 and the first fall frost is November 26. Here is when to plant sunflower against those dates.
Typical timing
Zone 9a planting schedule
Evidence trail
How these dates are built
Sprout applies the cited planting offsets to the typical zone 9a frost anchors. The result is a planning baseline for the zone, not a local weather forecast.
- USDA Plant Hardiness Zone Map, 2023USDA Agricultural Research Service / Oregon State University PRISM Group. Supports the USDA hardiness-zone band.
- U.S. Climate Normals 1991-2020NOAA National Centers for Environmental Information. Supports the median spring and fall freeze dates.
- SunflowersUniversity of Minnesota Extension. Supports direct-sowing timing (normalized).
Method note
Direct-sow timing (after all danger of frost; start-only anchor expressed as weeks 0-2 per store convention), 1 inch seed depth, spacing by height class (6 in for 2-5 ft varieties up to 24 in for giants), full sun, soil pH 6.0 to 6.8, problem list. No per-week water rate given, so waterInchesPerWeek is omitted; UMN advises regular watering 20 days before and after flowering.
These are zone 9a averages
Computed from 2,196 ZIP codes in zone 9a. Your town's frost dates vary; enter your ZIP for dates built on your nearest weather station.
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Put these dates to work
The plant profile covers spacing, light, water, soil, and source-backed timing details. The growing guide covers preparation, care, and harvest technique.