Allium dichlamydeum on the Wiki
Mary Sue Ittner (Sun, 25 May 2003 17:25:46 PDT)

Dear John,

This is a coastal species so may not be very hardy. It can take freezing
temperatures as it has for me, but the lowest we have gotten is 19 F. (-7
C.) and that was one of those rare events.
So I can't tell you, but maybe others who grow it can report how cold it
gets for them.

Mary Sue