I'm in Houston too and I have two established outdoor hibiscus plants, both have died back and frozen pretty good and then come back strong over the last several years. About now you should have some leaves budding out, mine has some serious re-growth and I thought it was dead and gone, even from stem material that looked terrible. I trimmed off the parts that proved to in fact be dead, and a little more here and there to regain its shape (I'd let them go for quite a while) and they are looking like they will do just fine.

If you don't have any new growth or leaves, I might give it a few more weeks and then pull it.

My problem/confusion is that my new from last year Rose of Sharon (Althea?)... had already leafed out - looked really beautiful, and then it was hit by the cold two nights in a row. The leaves are greenish/blackish and droopy. Is there hope for this shrub? Thanks

Carrie