I'm sorry no one has answered your question, i have the same question. My hydrangea made it through winter, but i made sure to go and water it on occasion. It really isn't protected from the wind much, but i live almost in downtown and we are warmer than the Northwest. So hopefully someone will tell us about winter protection for hydrangeas or are they just a pipe dream in the desert??

Okay a month later and everything is leafing out. These are half sun half shade medium water wind protected. Guess I got anxious.

My lace cap hydrangea came back well....looked dead a month ago but bushy now. Don't know if it will every flower...didn't last summer. I haven't tried mopheads here.

Oh, everything was heavily mulched over the winter.