Growing petunia in zone 5a
(Zone 5a = an average winter low of -20°F to -15°F.)
In USDA zone 5a, the typical last spring frost is May 3 and the first fall frost is October 5. Here is when to plant petunia against those dates.
Typical timing
Zone 5a planting schedule
Evidence trail
How these dates are built
Sprout applies the cited planting offsets to the typical zone 5a 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.
- Petunia (HGIC 1171)Clemson Cooperative Extension, Home & Garden Information Center. Supports indoor seed-starting timing (normalized) and outdoor transplant timing (normalized).
Method note
Sow-indoors offset (8 to 10 weeks before planting in beds), planting after frost danger (start-only anchor expressed as weeks 0-2), spacing 12-18 in, full sun, soil pH 6.0 to 7.0, problem list. Water rate converted: Clemson gives 1 to 2 inches every 7 to 10 days; recorded as 1 inch per week. Seed depth omitted (seed needs light, surface sown).
These are zone 5a averages
Computed from 2,383 ZIP codes in zone 5a. 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.