Feel free to cage them if the weather forecast calls for wintery temperatures, especially old wood blooming hydrangeas. Exactly when leaves will dry out and fall is an inexact science. If your gut tells you that it is time, cage them. I would not cut off the leaves as this sometimes triggers new growth. With your temps being so cold, I am not sure how the plant would react if you cut them off. The poor thing may try to put new growth.

Thank you luis_pr ! That was what I was thinking too. I was checking to see if anyone would tell me I was wrong !

I routinely put plants away for the winter while they still have green leaves. It's never been a problem. My first impulse was to think disease, but it never seems to be a problem.

Hay