Growing romanesco in zone 3b
(Zone 3b = an average winter low of -35°F to -30°F.)
In USDA zone 3b, the typical last spring frost is May 17 and the first fall frost is September 23. Here is when to plant romanesco against those dates.
Start seeds indoorsApril 5 to April 19
Transplant outdoorsMay 17
Expected harvestJuly 31 to August 25About 75 to 100 days from transplanting.
These are zone 3b averages
Computed from 224 ZIP codes in zone 3b. 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 romanesco from University of Wisconsin-Madison Division of Extension. Zone dates are medians; local conditions vary.