Keep it going for as long as you can!
I’m in Zone 5a (SW corner of Wisconsin) and in years with a thick layer of snow BEFORE freezing temps I’ve over-wintered Brussels Sprouts, Onions, Leeks, Kale and Spinach.
A good book on the subject is ‘Year Round Vegetable Gardening’ by Nikki Jabbour. She’s in Canada and gardens all year round under row covers and snow.
Also, anything by my HERO Eliot Coleman and his wife Barbara Damrosch. They garden in Maine:
https://www.eliotbarbara.com/read-our-books/
Bump for later! Thanks.