Project Description

Gymnocalycium mihanovichii

Moon Cactus

This cute “mutant” cactus is actually a combination of two cacti, typically Gymnocalycium (the sicon) and a rootstock cactus, such as Hylocereus. The term “moon cactus” typically refers to the yellow and orange varieties, however red varieties can be included.

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Quick Look:
  • Partial sun to partial shade
  • Can be grown indoors if given enough light

  • Typical water needs for a succulent

  • Plant grows up to 12″ (30.5 cm) tall
  • Zone 10a (Minimum 30° F | -1.1° C)
  • Not cold hardy

  • Propagation by grafting and offsets
  • Generally non-toxic to humans and animals

  • Actively grows in the Summer

Also available from Leaf and Clay and Etsy.

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Care and Propagation Information

General Care for Gymnocalycium mihanovichii “Moon Cactus”

Gymnocalycium mihanovichii “Moon Cactus” is a great cacti for beginners. It grows well indoors, and thrives on neglect. It is actually two separate cacti grafted together. The top, colorful graft comes from Gymnocalycium, with the rootstock cacti coming from another cacti. The colorful Gymnocalycium is a mutant, unable to photosynthesize, and therefore requiring nutrients from another cacti.

Watering

“Moon Cactus” has typical watering needs for a succulent. It’s best to use the “soak and dry” method, and allow the soil to dry out completely between waterings.

Where to Plant

“Moon Cactus” is not cold hardy, so if you live in a zone that gets colder than 30° F (-1.1° C), it’s best to plant this succulent in a container that can be brought indoors. It does well in full to partial sun.
Plant in an area of your garden that gets partial sun and shade. If planting indoors, place in a room that gets some sun and filtered light.

How to Propagate Gymnocalycium mihanovichii “Moon Cactus”

Not all Gymnocalycium mihanovichii “Moon Cactus” will produce offsets. Those that do can be propagated from the offsets. You can try to extend the life of your “Moon Cactus” by grafting it onto a new rootstock.

Offsets

Some “Moon Cactus” will produce small offsets, sprouting off of the top of the plant. Remove these carefully, and allow the offsets to dry for one to two days before placing in well-draining soil.

Pairs Well With

Kalanchoe tomentosa

Commonly Asked Questions

Question

I rescued this baby a few weeks ago and within days the bottom part began to get very soft and slimy so I put it outside in the shade and stopped watering it. The bottom has dried and seems to be holding its own. Should I cut it off and try to re-root it? Also The yellow part has produced “babies” should I be doing something with them or just leave them alone?

Answer

What a beautiful cactus! It looks like the top part, which has been grafted on, can be saved, but it’s possible the bottom may not survive.

If the bottom is dried out and seems to be doing ok, I’d let it continue to dry for another week or so and then begin watering again, following this technique.

However, if things seem to decline in the next week or two, you’ll likely want to regraft the yellow section of the cactus to a new base.

The “stem” of your cactus looks like Hylocereus. You can purchase another, and graft the top bulb (which appears to be a Gymnocalycium mihanovichii) to it.

The top “bulbs” are unable to survive on their own, as they are unable to make their own chlorophyll — this is how they have such vibrant colors.  Any babies removed from the top section will need to be grafted onto another stem in order to obtain nutrients.

To graft your cactus, you’ll need the following:

Tools:
A sharp, sterilized knife
Rubber bands
Well-draining soil
A new pot

I would suggest watching this video, and following the directions in this post.

Good luck, and happy grafting!

Rescue cactus drying out

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