Growing sweet alyssum in zone 4a
(Zone 4a = an average winter low of -30°F to -25°F.)
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 sweet alyssum against those dates.
Start seeds indoorsMarch 31 to April 7
Transplant outdoorsMay 5 to May 12
Direct sow outdoorsApril 14 to April 28
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 datesUSDA 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 sweet alyssum from NC State Extension (North Carolina Extension Gardener Plant Toolbox). Zone dates are medians; local conditions vary.