San Pedro

More about San Pedro

Together with Peyote, San Pedro is possibly one of the most famous mescaline cacti out there. Originally from the Andes mountains, it can be found in the mountain sides of Peru, Ecuador, Bolivia and northern Argentina. It is commonly found in the dry shrublands and high rainfall regions of the Andes at altitudes that go from 1500 to 3300 meters above sea level. One of the main characteristics of this cactus is its fast-growth, so if you are not very patient, perhaps a San Pedro will do you good. Under the right conditions, this cactus can grow up to 40 cm per year! 

Previously known as Trichocereus pachanoi, this cacti was mostly sold as an ornamental and psychoactive plant. For the indigenous population around the Andes, the San Pedro cactus has been known as an entheogenic for thousands of years. Its most ancient signs of use date back to 2000 years ago, in the Moche civilization. Called the “materia prima” by the shamans that made use of it, it was the main ingredient for their shamanic rituals as well as for their medicine. 

The common name for this cactus (San Pedro) suggests that the Spanish invaders were not very successful at punishing the use of this plant. Just like San Pedro  (Saint Peter, in English) had the keys to heaven, San Pedro (the cactus), was the “key to reach heaven while still on earth”. The indigenous population of the Andes say that the strength of the San Pedro cactus depends on the amount of ribs it has. They say those with 7 ribs are the least potent and those with 4 ribs are the strongest. 

San Pedro is a columnar cactus, meaning that it grows vertically, aiming at the skies. As it grows, it tends to form a small tree which can be anything from 3 to 6 meters tall by 1,8 meters spread. It is of pale green, somewhat bluish colour with stems that go from 6 to 15 cm in diameter. The ribs of the cactus range from 4 to 8 (usually 5 to 7) and they are uniformly covered by the spines, which tend to be about 2 cm apart. The spines are short (1 to 2 cm long) and of a dark yellow or light brown colour. When present, the spines may come alone or in groups of 3 to 7. 

The flower of this cactus, which tends to appear around July, is of large proportions, white and very fragrant. It blooms during the night and stays open throughout the following day. The flower buds arise from the spine clusters and, once developed, they present a layer of black curled hairs. The fruits that originate from these flowers are of a dark-green colour and have around 3 cm in diameter and a length of between 5 and 6 cm. 

It is very easy to grow San Pedro. Thanks to its origins, this cactus is used to enduring rather harsh conditions and, if given enough water and kept well fed, it will grow like no other, especially if it has been acclimatised to receive full sun. When first planting your sample, make sure to put it on a fertile and well drained soil mix. Having a good start is half of what you need for a fully healthy green pet. 

When it comes to watering, San Pedro is one of those cacti that can take a little bit more water than the usual. As long as the plant is allowed to dry before rewatering, it should be fine. During winter it should receive a bit less water than usual and keeping it dry is even more important, as moist could lead to the rotting of the roots. San Pedro can take temperatures as low as -12°C, however one should refrain from leaving it at temperatures below 10°C.

During the growing season, the cactus should be fed with fertilizers on a monthly basis. During winter, however, the grower should consider reframing from fertilizing and watering the cactus so as to induce winter dormancy. When it gets a little too cold and the sunlight is not as consistent (like during winter), you risk having your cactus go through etiolation. Making it go through winter dormancy prevents that from happening. Like most cacti, San Pedro is susceptible to fungal diseases if overwatered even if to a lesser extent than most other species. Keep it dry, however, and you shouldn’t have any issues with these types of infections. 

If you are considering growing other types of cacti but you struggle with the idea of having to wait for so long, you might consider using San Pedro as a grafting stock. Indeed, San Pedro is commonly suggested as a universal grafting stock for the smaller and slower growing cacti. Most photos of different cacti varieties show San Pedro as the base stock of the plant.

Nursing tips:

After delivery, place the unrooted cuttings in a pot with dry, well draining cactus soil and place them in a light spot but not in direct sunlight. After about a month, you may give it a little bit more sunshine and very carefully start watering the cutting. 

Make sure that you don't overwater the plant before it has roots and let it get used to full sunlight gradually to prevent sunburn. Allow for the soil to dry out between waterings, in spring or autumn you're going to water less then in summer and in the winter you don't need to water your cactus at all.

Scientific name

Echinopsis pachanoi (= Trichocereus pachanoi)