How to Grow a San Pedro Cactus Indoors

The San Pedro cactus (Trichocereus pachanoi) grows in a single, thick column. The flesh of the cactus is traditionally eaten or made into tea in Peru. Since the San Pedro cactus can reach heights of 19 feet tall, it is typically grown outdoors. However, you can also grow it in a pot placed indoors. Indoor San Pedro cactus plants remain shorter due to less light and restriction of the roots.

5- to 6-inch diameter plant pot

Gravel

Cactus potting mix

Water

Liquid cactus fertilizer

Potting soil (optional)

Perlite (optional)

Oven (optional)

Locate a 5- to 6-inch diameter plant pot ensuring that is has at least three to four holes in the bottom for water drainage. Fill the inside of it with a 1/4- to 1/2-inch layer of gravel to assist with drainage.

Fill the pot with a cactus potting mix, until it is half full. Cactus mix is available at any garden center or plant supplier. Water the mix until it is damp but not soggy and holds together when you squeeze it in your hand.

Put on garden gloves and carefully remove the San Pedro cactus from the nursery pot. Place the roots into the new pot and add additional soil mixture until it reaches the base of the cactus. Do not apply soil above the green portion. Water the soil again to moisten the upper layers.

Place the pot in an area with direct sunlight, such as a windowsill.

Water the soil in the pot once per week by filling a sink with 2 inches of water and placing the pot into it. Allow the top of the soil to dry completely in between watering. Stop watering in the late fall when the cactus goes dormant and resume again in the early spring.

Apply a liquid cactus fertilizer to the soil in the pot, choosing one that has numbers of 4-7-7 or 2-7-7. The numbers indicate the percentages of nitrogen, phosphorus and potassium in the product. Apply the fertilizer only at the suggested intervals on the package, since too much will cause them to deteriorate.

Move the pot to a cooler location in winter, such as a basement or even a shed. The optimal winter temperatures for a San Pedro cactus is between 40 and 50 degrees Fahrenheit, although it can survive indoors at room temperature as well.

If desired, you can make your own cactus potting mix by combining 50 percent soil and 50 percent perlite. Sterilize the mixture by placing it into an oven set to 180 F for one hour.

The San Pedro cactus is a source of the illegal drug mescaline, though it is legal to possess the living plant and grow it as an ornamental in the U.S.