Any time actually but why force them inside? In your zone/location they can easily thrive outdoors during the winter with just a bit of protection and will be much better flavored. Grown inside they turn bitter as they need that chill to sweeten.

Dave

Hmmm, if I allow them to grow outside, do I trim them down for the pale head and then cover with straw? It is not something I had considered before. I was planning to cover that bed anyway as there is gremulo rossa growing and I am waiting for the cold to turn it rosso.

Any updates on your endive?
This is the first time i've grown it. I've got some in 5 gallon buckets on a heat mat with black plastic garbage bags over them to exclude light. They have been sprouting for about 3 weeks and they look like this!

{{gwi:117059}}