Devils backbone can be propagated in water
The roots are the part of the plant you will put in water, then add some soil or sand on top of the roots and put it in a pot with water.
Keep changing the water until the roots are good and healthy. Then you can plant them in your garden.
Note: Devils backbone is a perennial plant that does not need to be replanted every year. It will keep growing for many years if well taken care of.