Does it need full sun?

Yes, it thrives in bright, direct sunlight for most of the day.

How often should I water it?

Water deeply during the growing season, but allow the soil to dry out completely between waterings.

Plant guide

San Pedro cactus.

Echinopsis pachanoi

Pronounced eh-kin-OP-sis pa-ka-NO-ee

Also known as Echinopsis pachanoi, San Pedro cactus

Trichocereus macrogonus — Photo by Thibaud Aronson (CC BY-SA) via iNaturalist

The San Pedro cactus is a fast growing columnar species native to the Andes mountains. It is well known for its tall, ribbed stems and night blooming flowers. This cactus is quite adaptable and makes a striking addition to sunny gardens or large containers.

Another photo of San Pedro cactus — Photo by Floro Ortiz Contreras (CC BY) via gbif

At a glance

Care level: Easy
Plant type: Succulent
Light: Full sun
Indoor light: Direct sun
Water: Every 14 to 30 days
Mature size: 3 to 6 meters
Growth rate: Fast
Hardiness: USDA 8 to 11
Bloom time: Late spring to summer

Care

Provide plenty of direct sunlight and use a well draining cactus mix to prevent root rot. Allow the soil to dry out completely between waterings, especially during the cooler months. Watch for soft or mushy stems as these are clear signs of overwatering.

Watering: Water deeply during the growing season but keep the soil nearly dry in winter.
Feeding: Use a balanced liquid fertilizer diluted to half strength during the active growing months.
Pruning: Prune only to remove damaged sections or to propagate using clean, sharp tools.
Repotting: Repot when the cactus becomes top heavy or outgrows its current container.
Soil: Sandy, well draining cactus mix
Soil pH: 6.0 to 7.5
Temperature: -4 to 40°C
Humidity: 20 to 50%
Drought tolerance: High
Lifespan: Perennial, can live for several decades.
Fragrance: Strong
Deer and rabbits: High

Signs it needs repotting

Roots growing out of the drainage holes.
The plant becomes top heavy and unstable.
Stunted growth during the active season.

Safety

People: The plant is toxic if ingested and can cause severe gastrointestinal distress or hallucinations.
Pets: This plant contains mescaline and other alkaloids, so it can be toxic to cats and dogs if chewed or eaten. Signs can include vomiting, drooling, wobbliness and unusual behavior. The spines can also cause physical injury.
Children: Keep this plant away from children due to its sharp spines and toxic chemical content.
Contact allergens: The spines are sharp and can cause mechanical skin irritation or puncture wounds.
Airborne allergens: There is no significant risk of respiratory allergy from this plant.
Edibility: This plant contains mescaline and other alkaloids, making it unsafe for consumption.

How to identify it

Columnar stems with four to nine ribs
Small spines often absent on mature stems
Large white fragrant night blooming flowers
Blue green to bright green skin
Distinctive V shaped notches above areoles

Height: 3 to 6m
Spread: 0.5 to 1m
Leaves: green, blue-green, evergreen
Flowers: white, 15 to 22cm
Fruit: green, Late summer

Problems to watch for

MealybugsCommon
Root RotCommon
Scale InsectsUncommon
Spider MitesUncommon

By symptom

Plant problems by symptom

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Growing it

Propagation: cuttings, seed
When to plant: spring, summer
Overwintering: Keep the plant dry and cool during winter to encourage dormancy. Protect it from freezing temperatures to prevent tissue damage.
In containers: It grows well in containers, provided you use a well draining cactus mix and a pot with large drainage holes.

Stem Cuttings

1. Cut a healthy stem section.
2. Allow the cut end to callous for two weeks in a dry, shaded area.
3. Place the calloused end into dry, gritty soil.
4. Wait for roots to form before watering.

Group with other drought tolerant plants that do not require frequent soil disturbance.

Grows well with

Agave · They share similar drought requirements and aesthetic desert appeal.
Sedum · These low growing succulents provide a nice textural contrast at the base.

Similar species

Peruvian Torch · It has a similar columnar form but typically features longer, more prominent spines.

Science

Family: Cactaceae
Genus: Trichocereus
Order: Caryophyllales
Class: Magnoliopsida
Native range: Andes mountains of Peru, Ecuador, and Bolivia.
Conservation: It is widely cultivated and not currently considered threatened in its native habitat.

It grows on rocky slopes where its shallow root system captures moisture from mountain mists.

Value to wildlife: night-blooming nectar source
Pollinators: moths, bees
Uses: ornamental specimen, xeriscaping, container gardening

Through the year

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Flowering

Fruiting

Foliage

Ecological indicators

Salinity: 1/9
Soil reaction: 6/9
Light: 8/9
Moisture: 2/9
Nutrients: 3/9
Temperature: 7/9

Taxonomy resolved against GBIF.

Questions people ask

Does it need full sun?: Yes, it thrives in bright, direct sunlight for most of the day.
How often should I water it?: Water deeply during the growing season, but allow the soil to dry out completely between waterings.

Where the name comes from

The name pachanoi honors Abelardo Pachano, a prominent Ecuadorian botanist.

Good to know

It is often called the San Pedro cactus.
The flowers are large, fragrant, and open only at night.
It can grow up to 30 centimeters in a single year under ideal conditions.

Also in

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This guide was generated with AI on September 26, 2026 and checked against GBIF taxonomy. It is general information, not horticultural or veterinary advice. Read about how we build these guides.