I'd just use snow, as and when available. Shovel as much loose snow over it as you can. In the wild, a tree that size would routinely be completely buried in snow.

Resin

The subject heading made me laugh...

"Winterizing a giant sequoia" -- obviously, in a giant house :O)

thanks, Resin. Snow is a good idea but eventually, when it gets colder, I'm going to secure a top on my burlap hut and I wouldn't be able to take it off and on when the snow inside melts.

If there aren't any concerns out there about the leaves, I think I'll give them a try.

Thanks again.

at what point would you let the tree try to survive winter on it's own?

With each year sequoias are supposed to get more cold hardy until about 12 years, when it reaches its full cold-hardiness potential.

I won't be able to protect it for that long so I figure I'll protect it a couple of more winters, if possible, and then hope for some subsequent mild winters. I'm located just outside its cold hardiness zone so hopefully it'll prove successful.