Yes, now is a good time.

The green variety is probably the hardiest but in previous years even they have taken a hiding from the cold winters. Unless you are living in a mild part of the country or you intend planting it in a sheltered position I would at least wait until spring and be selective as to where you intend to plant it.

They key is winter sun. All the ones that I know that pulled through 2010 got winter sun.