Ginny the good thing about hydrangeas is they can be rooted from cuttings so acquiring new varieties can be as easy as asking someone for a cutting or 2. If someone is willing to dig down at the base of a stem sometimes you can get a few roots already on the cutting and it makes the process a lot simpler.
If you want to multiply yours easily to trade plants or add more to your landscape you can scratch a little bark of a few stems and mound some soil around the stems in spring then dig down next spring before it starts leafing out and remove the limbs that have roots on them. The trick is to remove all the top growth except for 2 buds so when transplanted they won't die from transpiration. It also helps to grow them in pots for a few months so there is no weed competition for the young plant.
Rooting hormone is needed with cuttings but is not necessary with the mounding method. This method is called layering and it can be done with a bunch of different plants.
