Crown of Thorns will root easily into a good Cactus soil (sandy). Fresh growth tips will root better. Make sure you let the cuttings scab over before putting them into the soil. to avoid rotting. HERE’S A LINK to a post about rooting cuttings. It is rooting other plants but the procedure is the same for Crown of Thorns except you’ll be using a Cactus Potting Soil.