How to Grow a San Pedro Cactus Indoors

The San Pedro cactus (Echinopsis pachanoi, USDA plant hardiness zones 8 to 10) is a large cactus species that can be grown indoors. They require the same basic care as other plants, which makes them no more difficult to care for than any other cactus. With proper soil, light and water conditions, you can have a San Pedro cactus growing in your own home.

The San Pedro cactus is one of 131 Echinopsis types of cacti. They are native to the Andes, which are nestled between Bolivia, Ecuador and Peru. San Pedro cacti grow fast and tall and can thrive with ample warmth and light; however, they can also grow under partial shade. Established San Pedro cacti are drought resistant and only require moderate watering.

San Pedro cacti are cold hardy and can withstand cold temperatures down to 37 to 41 degrees Fahrenheit. Mature cacti can withstand direct sunlight; however, immature cacti can burn under direct sunlight in hot climates.

San Pedro cacti contain mescaline, a hallucinogenic substance commonly found in all parts of the cacti, including the flowers and fruits. Ingestion is illegal in most countries, though it has traditionally been used in many South American medicines and religious rituals. However, mescaline can lead to poisoning in children and pets, and it can harm adults who accidentally ingest it in larger doses. It's best to avoid the use of mescaline for these reasons.

Growing a San Pedro cactus indoors begins with soil. San Pedro cacti need porous, well-draining soil. This will prevent water from collecting in the pot and oversaturating the soil, which can cause root rot and other complications. Soil can be made more porous with the addition of perlite, sand, gravel or pumice. Look for a beginning cactus potting soil mix to ensure the soil has all that your cactus will need to flourish.

Fill the pot halfway with soil and then level it. Dig a hole that is 2 to 3 inches in diameter and carefully place the cactus in the pot. Add soil around the cactus until the roots are fully covered and tightly pack it. Water the cactus until the soil is damp but not saturated.

Water your cactus once a week using the bottom-watering method. Fill a sink or container with 2 inches of water and dip the pot so the water seeps through the drainage holes at the bottom. Remove it from the water once the soil is damp. If you choose to water with a watering can, water the cactus in sections throughout the week to prevent oversaturation.

San Pedro cacti are dormant between October and April and won't require watering during these months. Watering at this time will cause the roots to rot or will create an environment for bacteria, leading to infections.

San Pedro cacti benefit from liquid fertilizers as well. Following the manufacturer's instructions, apply a liquid fertilizer once the cactus has established itself in the container, usually four to six weeks after planting.

Slowly introduce the San Pedro cactus to sunlight by placing it in a location that sees both shade and sunlight throughout the day. You may also put your cactus under the morning or evening sun.

Once the cactus is accustomed to sunlight, make sure your cactus receives ample light while it grows indoors. You could also place the cactus outside under direct sunlight but be sure to water consistently, as this will dry out the soil faster.