Things You'll Need
Sharp knife, sterilized with rubbing alcohol
Cactus potting soil
Planter with drainage holes
Liquid cactus fertilizer
The San Pedro cactus grows quickly and, with proper care, it takes well to most environments. While starting this columnar cactus from seed requires little work, you can produce a larger and faster-growing cactus through cloning. The best method for cloning is to take a cutting of a San Pedro cactus and provide it with ideal root growth conditions.
Put on a pair of leather gloves and select a healthy column to cut from the San Pedro cactus. Slice the column off at least 8 inches from the top with a sharp, sterilized knife. The cutting can be however big you would like.
Set the cutting on a clean surface, in a dark place with plenty of air ventilation, for two weeks to heal. The healing process reduces the risk of fungal infection; when healed, the cut area will look dry and shriveled. Since the San Pedro is tolerant of droughts, this does not harm it.
Combine a 3:1 mixture of cactus potting soil and crushed pumice in a clean planter. The pumice ensures soil drainage to prevent rotting.
Plant the dried San Pedro cutting in the potting soil mixture 2 inches deep. Pack the soil around it so it stands upright and leave it in a cool, sunny area for two weeks without water.
Mix half of the manufacturer recommended amount of liquid cactus fertilizer with a full amount of water. A full ratio of liquid fertilizer might damage the fresh roots. Water the cactus, soaking the soil, until it begins to seep out of the drainage holes. Do not water the San Pedro cactus again until the soil is dry throughout.
Keep the cloned San Pedro in a cool, sunny area and continue to allow the soil to dry completely between each watering. Apply the fertilizer-and-water mixture twice monthly, mixed at the full manufacturer recommended ratio.
You can take several clones from one column of San Pedro cactus; the top is not required for survival. Mark which end is the top of the cut section, as roots will not grow from this end. The planter you select should allow about 2 inches of soil on all sides of the San Pedro column and should be at least 6 inches deep.