How to Propagate a Moon Cactus With Grafting
Understand the unique two-plant anatomy of a moon cactus and learn the specific grafting method needed to successfully propagate its colorful offsets.
The moon cactus, known scientifically as Gymnocalycium mihanovichii, is a popular houseplant with a vibrant, colorful top. Propagating this cactus is a rewarding experience that requires a specific grafting technique to create new plants.
Understanding Moon Cactus Anatomy
A moon cactus is two different cacti joined together in a process called grafting. The colorful top is the scion, a mutant variety of Gymnocalycium mihanovichii that does not produce its own chlorophyll. This lack of chlorophyll is what gives the scion its bright color, but it also means it cannot perform photosynthesis.
To survive, the scion relies on the green cactus it is attached to, the rootstock. The rootstock, often a Hylocereus cactus, carries out all life-sustaining functions, providing nutrients and energy. Any pups that grow from the colorful scion also lack chlorophyll and will need to be grafted onto a new rootstock to survive.
Propagation Methods for Moon Cactus
The primary method for creating a new moon cactus involves propagating the small pups that emerge from the colorful scion. This is accomplished by carefully removing a pup and grafting it onto a new, healthy rootstock plant.
A secondary propagation method focuses on the rootstock itself. The green Hylocereus base can be propagated by taking cuttings from its stems, which can then be rooted to grow a new plant. It is important to understand that this method will only result in a new green Hylocereus cactus, not a colorful moon cactus.
Step-by-Step Grafting Guide for Pups
To begin grafting, you will need several items. Disinfect your tools with alcohol before you begin to prevent the introduction of pathogens.
- A healthy parent moon cactus with pups at least half an inch in diameter
- A new rootstock cactus like Hylocereus
- A sharp, sterile knife or razor blade
- Rubber bands or twine
First, gently remove a pup from the parent scion by carefully twisting it off, or you can use your sterile blade to make a clean cut. Once the pup is separated, prepare the new rootstock by making a clean, flat, horizontal cut across the top of the cactus.
Next, make a fresh, flat cut on the bottom of the pup you removed. Place the pup onto the center of the freshly cut rootstock, carefully aligning the circular vascular rings in both the pup and the rootstock. This alignment allows for the successful transfer of water and nutrients.
Once the pup is positioned correctly, secure it firmly by stretching one or two rubber bands from the top of the pup down to hook underneath the rootstock’s pot. The pressure should be firm enough to hold the two pieces tightly together without causing damage.
Post-Grafting Care
After the grafting procedure, place the newly grafted cactus in a warm location that receives bright, indirect sunlight. Direct sunlight can be too intense for the delicate graft and may cause it to fail. Avoid watering in a way that allows moisture to sit on the graft union, as this can lead to rot.
Water the soil sparingly, only when it has dried out completely. The rubber bands securing the graft should remain in place for two to three weeks to give the union enough time to fuse. A successful graft will result in a scion that remains firm and retains its vibrant color. If the graft has failed, the pup will often shrivel, become discolored, or fall off the rootstock.
Common Propagation Issues
One of the most frequent problems is graft rejection, where the scion and rootstock fail to fuse. This can happen if the vascular rings were not properly aligned or if the two plants were not compatible.
Rot is another common issue that can occur at the graft union. It is often caused by using tools that were not properly sterilized or by allowing water to settle on the cut surfaces during the healing process.