Ever winter my angel trumpet dies to the ground even though our winters are mild. How can I take cuttings to survive the winter?

I think you might need to give more details on the size and age of the plant
i have rooted in water and soil - but not managed to get a cutting from a sanguinea

I forgot that I had put up this post. Now I have it posted twice.

My bush dies to the ground every winter. The one I have now is about six inches tall and growing.

Edit: the stump/roots are about 4-5 years old.