Stop working so hard ! Just lay them down on some soil ! In 2-3 weeks you will notice some roots then plant it and once a week give it a shoot of water . Cause most people over water them .[emoji217]
Yeah but some people have hard rocky clay instead of soil.
I am surprised that with the method i used here, the roots still seem to go deep enough to survive winters. Of course i will have to replenish the mulch occasionally. I water them some in the dry parts of the summer.
When i lived in Austin i sometimes saw opuntia ("nopales") growing out of vertical rock outcrops. As long as there is a slope for drainage they don't seem to require much soil.