Taking cuttings from a cactus plant is an easy method of propagation, as long as you're careful around the spines! Pad-forming, columnar, or segmented cacti can all be cloned in this way. Since cacti are drought-tolerant, cuttings will not suffer when exposed to the air, and actually prefer to dry out in order to propagate. Ideally, plant in the springtime when cacti are beginning to initiate new growth. Cuttings will only propagate successfully during certain months. When nighttime temperatures are 60 degrees F and above, its a good time to take cuttings.
Cut a cactus segment using a sharp, clean knife -- ideally, serrated. If cloning a pad cactus, cut between the pads. Cut a columnar cactus anywhere along the stem at a 45-degree angle. Cuttings can vary greatly in size, from immature globes to meter-long stem pieces.
Square off the base of the cutting and let it sit in a warm, dry place until it dries. If it is not allowed to dry, the tip may rot. Wait until a callus forms, which will protect it from soil-borne diseases. This can take one to 14 days.
Fill growing containers with a propagation mix of 1/2 organic and 1/2 inorganic material, ideally peat or compost and pumice or perlite. Place cuttings deeply into the mix, ensuring they will not topple over. Columnar cacti may need to be placed especially deep.
Provide plenty of sunshine and cool temperatures for the first few months as the cutting is taking hold. Avoid over-watering in these early stages, as it may lead to rot. Gallon-size containers can sustain the cuttings for the first year.