is it the cold weather or the frost that kills a plant during the winter?

... i was wondering if it was just cold air or is it something deeper? because where i live, it has been sunny almost everyday, and is going to be until spring. no snow and very little rain. but the temperature is still 40°F-50°F during the day and probably 20°F-30°F at night. i wanted to know if i could put a plant out or would it die?

I've never tested this theory, but It's my understanding at around 50F and below is when growth will stop. Not sure what temp will actually kill.

Water expands when it freezes, so a frost breaks the plant cells since they're mostly water.

The cold is the killer.

Growing citrus in Fl, when the occasional freeze came along, you would spray the trees and fruit down with water. It would freeze at 32* and keep the trees and fruit from going colder. Slight burns but no major damage. Un wetted trees and fruit that went down to the mid 20's or lower would be killed.

MJ is more sensitive. It freezes, it dies, so even a light frost is too much.

Wet

cold night and mild days would be ok such as spring but cold night and cold days will finish the weed off.