I think the cabbage should be ok because it's a cool weather crop and can take a frost. The onions I have no idea never grown them. Good luck!

Onions are very frost hardy.

Thanks. I am not really that concerned about whether the onions and cabbage live through this cold snap. Let's face it, the warm fall we've had so far has been amazing but not likely to continue forever.

Rather I am more concerned about whether being out in 18-20F temps for a night or two will harm the storage/eating qualities of these plants. Hate to have to process all the onions because they froze instead of letting them sit in cold storage for the winter.

18-20 would be too hard a frost for me to risk them. I'd harvest them rather than risk the storage ability. JMO

Dave

My opinion would be that young onions are very frost tolerant but that onions you want for storage should be pulled. I had a touch of frost that nipped some of the cukes earlier in this week and it is supposed to get colder here this weekend so the onions I want to keep will be pulled.

20 degrees is too low for cabbage family