Here in North Texas, I usually cut them back to about an 8" tall stump. I use the grey or oldest "wood" cuttings ( 6" or longer) and root them in water. Mine are all in pots and not in the ground. Even though I know of people that over-winter theirs it the ground.
While in winter storage, you 'll need to check the soil moisture and water weekly, bi-weekly or monthly depending on temps and dryness.
Lonnie

"So should I take cuttings from * all* of the green growth, since it will die anyway? ... all the way back to where the growth has started to harden? " I had the same questions. What I found out is that all of the new growth doesn't necessarily die back, particularity if they get the right amount of water. I insert a bamboo skewer into the soil to judge.

Like yours, my plants are still of manageable height. I removed all of their leaves and sprayed them down with "Wilt-Pruf" to prevent/lessen dessication and moved them to the cool and dark basement. They're still blooming down there. ))

Gail

I have tried to water root green cuttings without success.
I hear of others that have done it, but with a lot of special care. I usually trim them up, keep the nice thick old wood and compost the small green cuttings. I did receive a few cuttings from Florida and one is green. I'm going to give it a try.
Lonnie