The San Pedro cactus (Trichocereus pachanoi) is a tall, multi-stemmed, columnar cactus native to southern Ecuador and Peru. It has been cultivated in Peru for many centuries, and is now widely grown in many parts of South America. Its ribbed upright stalks are studded with clusters of small thorns. It produces pretty white flowers, which open at night, and, rarely, tasty red fruits. The San Pedro cactus is very hardy, and tolerates a wide range of conditions. It is easily propagated by stem cuttings, and grows well indoors in large pots or planters near a sunny window.
Select an unblemished, 1-foot stem section from a healthy San Pedro cactus. Stick a small piece of masking tape on the side of the section that is exposed to the most intense sunlight.
Wear gloves and carefully cut the stem from the parent plant with the sharp knife. Try to make the cut at a node, for faster rooting.
Place the cutting in a dry, well-ventilated place out of direct sunlight for three days to one week, until a dry callous forms over the cut end.
Fold several pieces of old newspaper into a thick, 3-inch wide strap. Loop the strap around the middle of the stem to lift and steady the cutting. Plant the cutting in a 6-inch pot filled with loose, well-drained potting mix. You can buy special cactus potting mix or make your own, using one part pea gravel, one part perlite and one part peat moss. Transfer the masking tape from the cactus to the side of the pot to mark which side was receiving the most sun.
Water the cutting well at planting time, but wait until the top 1 inch of the potting mix is dry before you water again. Water carefully while the cutting establishes roots. You can water more frequently, for faster growth, once the plants are established.
Place the new cutting in bright, filtered sunlight, until it is well-rooted and new growth appears. Gradually move your cactus into direct sun, using the masking tape on the side of the pot to orient the plant the same way it was originally growing.
Feed your growing cactus with half-strength balanced liquid plant food once in early spring, and again in midsummer.