Growing sweet corn in zone 3a
(Zone 3a = an average winter low of -40°F to -35°F.)
In USDA zone 3a, the typical last spring frost is May 29 and the first fall frost is September 5. Here is when to plant sweet corn against those dates.
Typical timing
Zone 3a planting schedule
Evidence trail
How these dates are built
Sprout applies the cited planting offsets to the typical zone 3a 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.
- How to Grow Sweet Corn in Your GardenUtah State University Extension. Supports direct-sowing timing (normalized) and days to maturity (direct).
Method note
Direct-sow window start (plant after the last frost-free date; the two-week span follows the store convention from the tomato exemplar), days to maturity (60 to 90 from planting), full sun. USU spacing (7-9 in, rows 24-30 in) differs from UMN; UMN stored as the primary source.
These are zone 3a averages
Computed from 17 ZIP codes in zone 3a. Your town's frost dates vary; enter your ZIP for dates built on your nearest weather station.
Get my exact datesKeep planning
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.