Growing dahlia 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 dahlia against those 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 dahlia from Penn State Extension. Zone dates are medians; local conditions vary.