Moon Cactus
Gymnocalycium mihanovichii Origin: South America
Native to the deserts of South America, this succulent is actually two cacti grafted together. Unable to produce chlorophyll, the colorful cactus on top relies on the bottom cactus—known as a rootstock—to provide it with the nutrients it needs to survive. Though its lifespan is relatively short, you can propagate your Moon Cactus by planting the offsets that sprout from the top of the cactus.
Common Issues
Soft stems: This is almost always the result of overwatering that has led to bacterial rot developing in the thick, slow-growing stem tissue.
Beige patches: Your plant has most likely been sunburned. Try moving it to a shadier spot.
Light: This cactus prefers bright light. A southern exposure in the home is preferable, but a western exposure should also work well.
Water: Be careful not to overwater your cactus—consistency is what it needs. To discourage root rot, you should let the soil dry between waterings, but avoid leaving it dry for extended periods of time.
Humidity: Keep your Moon Cactus in a moderately humid environment to help prevent pests like spider mites from colonizing the plant.
Growth: The colorful bulb will grow to about 2 inches, while the size of the rootstock will depend on the species. The difference in speed can eventually destroy the graft, but it’s easy to transfer the top onto another rootstock.
Soil: If you water carefully, general potting soil works well. If you water with a heavy hand, opt for a porous potting mix with plenty of sand, perlite, or fine bark to increase drainage. A slow-release fertilizer is best.
Temperature: While cacti can withstand near freezing temperatures, we recommend keeping yours above 60°F.
Repotting: Most cacti have very small root systems, so you probably won’t have to repot yours for years at a time. It’s better if they become rootbound than for them to sit in excess soil.
Extra TLC: Opt for an unglazed pot with plenty of drainage holes, and consider adding a layer of gravel to the bottom of the soil.