How do you root these cuttings? I've tried on a few occasions and they never took - just rotted.

I have never tried, but from what I understand you put them in water til they root. please if anyone knows anything special about rooting these post.

the way i have rooted snail vine or any other vine is by taking a vine at least 18 inches long wrap around your four fingers a couple of times then take it off your fingers and place it in a pot of potting soil you .will have a circle with a little piece about 3 inches long left over cover circle with soil leaving the little piece sticking out ..circle will root and little piece will sprout new growth..and yes what you have is snail vine not corkscrew

Thank you Gloria for those instructions. I was also told this:

Snail vines are also easy to propagate from cuttings. Take cuttings in early spring once foliage is growing. Cut a 6-inch piece of plant using clean clippers.

Fill a small 3-inch growing container with perlite and moisten it. Remove leaves from the lower part of the cutting. Dip the cutting in rooting compound. Make a hole in the center of the perlite using a pencil and insert 2 inches of cutting into the hole.

To retain humidity, place the container in a clear plastic bag and seal it. Place the bag in indirect light. Check the cutting weekly for resistance when pulled. Transplant Vigna caracalla snail vine in the fall before cold weather comes.