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Sprout Authority

Growing petunia in zone 4a

In USDA zone 4a, the typical last spring frost is May 12 and the first fall frost is September 28. Here is when to plant petunia against those dates.

Start seeds indoorsMarch 3 to March 17
Transplant outdoorsMay 12 to May 26

These are zone 4a averages

Computed from 795 ZIP codes in zone 4a. Your town's frost dates vary; enter your ZIP for dates built on your nearest weather station.

Get my exact dates

USDA Plant Hardiness Zone Map, 2023. USDA Agricultural Research Service / Oregon State University PRISM Group. NOAA National Centers for Environmental Information, U.S. Climate Normals 1991-2020. Planting windows for petunia from Clemson Cooperative Extension, Home & Garden Information Center. Zone dates are medians; local conditions vary.