Tips For Growing A Mexican Fence Post Cactus Indoors (And Mistakes To Avoid)

If you want to go a step beyond houseplant favorites like the peace lily and the spider plant when adding greenery to your home, one of the best additions to consider is the Mexican fence post cactus (Pachycereus marginatus). This cactus is often grown outdoors in hotter climates to create a living fence – hence, its name. However, it's also a perfect cactus for your indoor space and is easy to care for, as long as you have the room for it. Be aware that this cactus can grow to a height of 15 feet or more, although it should remain smaller when kept in a pot. While Mexican fence post cacti aren't toxic, their spines can be harmful to touch or ingest, so be sure to keep your plant out of reach of pets and children. To help your cactus thrive indoors be sure to avoid overwatering, provide it with adequate light and temperature conditions, and ensure the cactus has the right growing medium and fertilizer.

As you would expect, this central Mexican native prefers a dry environment, so don't water it too much. You can tell the cactus has been overwatered if it starts to yellow or droop. It may also have a squishy texture, especially towards its base. Monthly watering is ideal during most of the year and is all it will need to thrive.

As you might expect, the Mexican fence post cactus needs a lot of sun. So put it in an area where it will get plenty of it, such as by a south-facing window or in a sunroom. The plant can grow well in either full sun or partial sun, but should ideally get at least four or five hours of direct sunlight each day. If this isn't possible, consider using a grow light to ensure it stays healthy. Avoid placing your cactus in areas where it could be vulnerable to cold drafts or sudden temperature changes. While the Mexican fence post cactus is hardy down to 25 degrees Fahrenheit, it grows best in temperatures above 70 degrees.

It's important to choose the right growing medium for your Mexican fence post cactus. This spiky plant grows best in well-draining, sandy soil. A typical cactus potting mix such as Miracle-Gro Cactus, Palm & Citrus Potting Mix should work well. Consider using a diluted liquid fertilizer monthly throughout the growing season, but don't overdo it. Avoid providing any fertilizer during fall and winter.