How To Graft Moon Cactus? [6 Steps and Video Tutorial!]


Many people didn’t know that a colorful moon cactus is two distinct cactus species joined to make one unique plant. I met newbie plant collectors who thought that the bright top of the moon cactus is a flower and often asked me how to create this impressive cactus.

To graft a moon cactus, you have to 1) cut-off the top of the rootstock with a sterile knife, 2) slice the bottom of the scion, 3) mount the scion on top of the stock – vascular tissues overlapping, 4) fasten the graft securely with an adhesive tape or rubber band, 5) apply sulfur powder to the open wounds, and lastly 6) set aside in a shaded, dry spot to heal.

Because of their amusing appearance, moon cacti are popular among cacti collectors who want a splash of color in their surroundings. Propagation through grafting is the key to keep these vibrant cacti growing.

Do you want to make one? Check out what I do as a professional with my moon cactus for my clients and me.

Moon Cactus: The Union of 2 Different Plants

Notice that a moon cactus has two different parts, the colorful rounded head, and the green base. These parts are two various cacti species joint (grafted) to form one new plant.

Grafting is a technique of cutting and merging two plant varieties to make another one. In the same way, a Gymnocalycium mihanovichii mutant grafted in a Hylocereus undatus (or other cacti species) form a new plant called ‘Moon Cactus.’

The Mutant Head

The moon cactus has a spherical head referred to as ‘scion.’ The scion of a moon cactus is a cultivar of Gymnocalycium mihanovichii.

When we say cultivars, we mean a plant that has undergone a genetic selection due to human intervention by breeding and propagation, etc. The transformation allowed over the years to alter the pigmentation of the cultivar, exposing other pigments that were initially hidden by the chlorophyll. There is nothing new here; this is the same process by which humans have created so many different types of dogs. Thus, they have vibrant neon colors of yellow, pink, red, and orange. They lack chlorophyll. Photosynthesis is impossible, and that means they will die on their own.

The head of a moon cactus cannot survive independently and cannot be planted as a typical cactus would do. Hence, they need a green base cactus to continue their lifespan.

Moon cactus produce babies around their bodies that look exactly like them. The babies are the subject for propagation. When these moon cactus babies grow in size, they can be removed and grafted. They serve as the scion in making another moon cactus. But of course, with the help of a base cactus or the rootstock.

The Sturdy Base

The colorful moon cactus head will not survive without its sturdy green base. The base, referred to as ‘rootstock,’ serves as the host for the top cactus that acts as a parasite.

For grafting, the ideal rootstocks should be sturdy, green, thick, actively growing, and fungus-free. The choice of rootstock will also depend on the variety of scions. The compatibility of both rootstock and scion is imperative for a successful graft.

Compatible rootstock cacti species for Gymnocalycium are Hylocereus (commonly used), Myrtillocactus, Trichocereus pachanoi, Harrisia, Cereus, and Stenocereus. They are the best rootstock for grafting because of their resilience to temperature variation. Most local cacti shops sell these kinds of cactus species. Hylocereus is abundant in farms that sell dragon fruit.

How Is Moon Cactus Grafted?

Grafting the moon cactus requires precision in attaching the scion to the stock. Merging is the critical part of grafting as it may determine the success of the graft. The grafting should be done as quickly as possible to prevent any contamination.

Below you can find simple and easy steps in making/grafting the moon cactus pup I use with Hylocereus rootstock. But first, you have to prepare all the things that you need.

Supplies Needed For Grafting

To graft a moon cactus successfully, it is necessary to consider grafting in areas where you can leave the graft unmoved and dry. Here are things you need:

  • Work area: Use a flat table with all the supplies you need on top for smooth and convenient movement. I highly recommended a workspace that is well-lighted and comfy. Be sure it is disinfected (alcohol) beforehand to lessen the presence of pathogens that might otherwise affect the grafting results;
  • Scion: Healthy, good-sized moon cactus pups for the scion
  • Rootstock: Well rooted and actively growing rootstock for the base
  • Cutting tool: Sterile and sharp cutting tool for a clean and precise cut. The thinner, the better.
  • Disinfectant: alcohol/peroxide to avoid contamination and transmission of germs
  • Tissue: this is for wiping
  • Gloves: if you are sensitive to spines
  • Adhesive tapes or rubber bands: to secure the graft

Before starting the first cut, make sure that all tools are disinfected, including your hands. It is essential to work on clean space using clean tools. The reason is simply to avoid germs getting into the cactus wound and cause infection or rot.

Step by Step Guide on How To Graft a Moon Cactus

Video Tutorial: Step by Step Guide on Moon Cactus Grafting

Once the material is ready, you can jump to the grafting following my 6 step approach. Later you will also find a video!

Cut Off The Top of the Rootstock (Hylocereus Undatus)

First, sterilize your cutting tool before making the first cut. I usually use a sharp knife.

Chop off the head of the rootstock with the knife. The wound should be flat, straight, and precise. Leave at least a height of 5 inches above the soil. The longer the rootstock, the more light it will receive.

Then, chamfer the sides of each rib at an angle. You need to chamfer to hinder the rootstock from forming new shoots right on the top where spines grow. New offshoots growing on the top of the rootstock will affect the growth of the scion. Chamfering will also prevent any shrinking on the stock or the scion pushing the graft away, resulting in a failed graft.

Cut Off The Bottom Of The Scion (Moon Cactus Pup)

Sterilize the knife again with alcohol before cutting your scion.

Start slicing a thin part on the bottom of your scion and cut as flat and straight as you can. You may repeat as necessary but try to make your slices as thin as possible. You can notice a white ring-like thing on its core called the vascular tissue.

Vascular tissue is the tissue of plants composed of xylem and phloem responsible for transporting water and foods throughout the system.

Mount The Scion On Top Of The Rootstock

This step needs a steady pulse and quick action. I usually make another last thin cut off the rootstock and scion before joining both parts; it should be simultaneous.

Quickly position the moon cactus scion to sit on top of the rootstock and join them before they start to dry out. Make sure their vascular tissues overlap. Gently put a little pressure on the scion (be careful not to apply much force) and twist it a bit to remove trapped bubbles under the cut. The trapped bubbles will hinder the scion from attaching to the stock completely. Make sure that their vascular tissues are aligning or intersecting.

Fasten The Graft

After mounting the scion beautifully, fasten the graft to secure the scion firmly to the rootstock. You may opt to use any fastening tool like strings, twist twines, rubber bands, or adhesive tapes. I prefer using adhesive tapes because I can control my pulse and put just the right amount of pressure. I do it by twisting the center portion of the adhesive tape, forming a twine.

Then position the twined tape on top of the scion, work your way down, adding a little pressure while pulling. Repeat, but this time fasten the tape perpendicular (90-degree) to the first one making a criss-cross. Setting the scion is tricky because wrong centering and too much tension will cause the scion to slip and slide.

Apply Sulfur Powder On The Side Cut (Optional)

After securing the scion on the rootstock, you can apply sulfur powder to the exposed cuts. Sulfur powder inhibits microbes from getting into the tissues of the rootstock and may cause infection and rot.

Set Aside To Heal

The final step is to transfer them to a shaded area with good air circulation as the graft begins to bond. This condition will help the graft heal better. Avoid touching the scion as this will disturb the union of both tissues. Keep them from getting wet and cut back from watering as it may sometimes cause the unhealed tissues to rot.

Usually, a moon cactus graft requires a week or two to recover from grafting.

Check the wounds first if it is entirely dry and calloused. But I recommend giving another week just to be sure that everything under the cut is connected. By this time, the scion and the rootstock are entirely attached. Remove the adhesive tapes carefully while holding the scion so as not to knock them off. If you are using rubber bands, slowly pull the top side to remove it.

After Care

Gradually introduce your new moon cactus to bright shade and moderate watering as it is still acclimatizing. When you do the watering, do not wet the top graft. Instead, pour the water directly into the soil. Water will dwell on the cuts and may breed fungus that will cause rot.

2 Grafting Tips

The right timing and the excellent rootstock can dramatically improve the chances of successful grafting.

Timing

The best time to graft a moon cactus (or any other cactus) is from spring to summer. During this time, the cactus is starting to awaken, then new growth appears. Some begin to graft during the end of the winter season and still get successful results.

Rootstock

Water your rootstock before grafting. The reason is for the rootstock to store enough water and withstand several weeks of drought. Dehydrated rootstock will shrink as the wound cut starts to heal callous.

Choose a young, sturdy rootstock for the scion for the grafting. Old rootstock usually has woody cambium that is difficult to cut. Woody cambiums are typically dry. There might be a low chance of success when grafted.

Signs Of Success Grafting

The most common sign of a successful moon cactus grafting is the growth of a new spine from the apex of the scion. Success graft happens after around two weeks.

This means that the vascular cambium of the scion and the rootstock merged effectively. Water and nutrients are transported efficiently up to the scion. Usually, if the scion takes on the rootstock, it will show after 7 to 14 days. However, sometimes it takes a few more weeks. So, you need to be patient with your moon cactus and don’t give up on it right away.

The 3 Signs Of Wrong Grafting

Grafting can be fun and exciting, especially if you have done it successfully several times. But it is inevitable to fail sometimes in grafting, especially if you are a beginner. There are some factors you need to assess if you experience a failed graft.

Here, I will tell you the problems I encountered as a professional gardener and the techniques I discovered through the years of grafting cactus.

Dried Out Scion

You may notice that the scion is slowly drying out after a couple of weeks and has no signs of growth. They appear to be shriveled, and eventually, after few days, they fell off. What seems to be the problem?

Incompatibility

Scion often dries off and falls because it got rejected by the rootstock. In other words, the rootstock and the scion didn’t intermingle because they are incompatible with each other. It is best to know the rootstock species you are using and make sure that it is compatible with the scion you are using. (Rootstock species compatible with Gymnocalycium discussed above.)

The Cut Is Not Fresh

Cactus tissues dry off fast when exposed to air. Dry cuttings will stick poorly because the sap dries off even before they were attached. Thus, the merging of tissues between both cacti is unlikely to happen. Cutting and joining the rootstock and scion must be done quickly indeed.

Wobbly/ Mushy Scion

A mushy scion is brown and watery. It becomes wobbly and is soft to touch. There are two possible reasons why the scion turns mushy.

Fungal/bacterial Infection

Cacti tissues are soft and vulnerable to microbial infections. An unsterile blade or unsanitized hands and surroundings may be the reason why your moon cactus scion gets infected. It is necessary to disinfect everything that comes in contact with your scion and rootstock. The sulfur powder can be helpful, too, to inhibit the pathogens.

Water Settled On The Wound

Fresh cacti wounds should be kept dry. Wet surfaces are the breeding grounds of fungus. If a cacti surface stays moist for several days, the fungus will probably form on the skin. Eventually, the fungus will get into the system, causing your cacti plant to rot. I suggest keeping your plants in a dry place and avoiding getting them wet.

No Growth in the Scion

Sometimes, the scion and the rootstock already adhere to each other, but no growth is visible even after several weeks. It is either because the union of vascular tissues did happen or the scion you used is not actively growing.

Failed Union of Vascular Tissues

The crucial part of grafting is overlapping and securing the vascular rings of both cacti firmly. These rings should intersect before the healing phase because that’s where the union will start. When vascular tissues fail to unite, the graft will be unsuccessful. Always be mindful when attaching both cacti because it will significantly affect their performance.

Inactive Scion

Scions in the dormant phase will not show signs of development even after grafting. Probably their tissues are aligned, but progress is invisible. However, it will remain attached to the rootstock until dormancy ends. Don’t give up yet because if the scion awakens, it will start to puff and flourish.

Broken Moon Cactus

A broken moon cactus still has the chance of survival. As long as the tissues are intact and the vascular cambium is present, grafting is still doable. In cases when the rootstock dies, moon cacti with pure variegation must be re-grafted to a new rootstock to extend their life span. They are unlikely to grow on their own because they don’t have chlorophyll. However, there are moon cacti mutants that contain patches of green pigments on their body. These mutants can survive without grafting, but their life span can be short.

Two types of moon cactus – Partially Variegated (Left) and Fully Variegated (Right)

There is nothing to worry about the rootstock when the scion dies. The rootstock is independent. It will just continue to grow even without the scion. You may reuse the rootstock to graft another scion or just plant them directly into the soil.

What Cactus is Used For Grafting?

Any cactus is suitable as scions for grafting in proportion to the size of the rootstock. However, not all cacti are fit to use as rootstock. Indeed, a rootstock must be thick and sturdy enough to support the graft.

Cacti species that make a good stock are Hylocereus, Harrisia, Trichocereus, Acanthocereus, Myrtillocactus, Stenocereus, Opuntia maxima, Cereus, and Selenicereus. They commonly used rootstock when grafting small to large-sized scions. Pereskiopsis spathulata and Harrisia Balansae are used in micrografting because they are fast growers that propel the growth of the seedlings.

Trick Tools in Grafting

Over the years, I’ve learned tricks and techniques that make grafting cactus even more enjoyable and successful. Some tools and materials come in handy when grafting.

Blades: Scalpel ar razor blades are thin and can make a thin slice without damaging the tissues of your cactus, specifically the scion. It can make a precise cut with ease and comfort. Just make sure to sterilize the knife before use.

Rubber band: Another trick tool is the rubber band to secure the scion to the stock. These are used in larger grafts to ensure proper attachment. Use rubber bands that are not too loose or too tight. If it is too loose, it won’t be able to hold the scion firmly enough. At the same time, too tight rubber bands will cut the scion.

Parafilm: This can also be helpful when grafting small scions. Small scions tend to dry out fast. Parafilm is used to fasten the scion on top o the graft. It helps reduce moisture loss within the scion because it encloses the graft wound.

Grafting Techniques For Cactus

There are several methods to graft a cactus according to the style of cut made in the rootstock.

The Flat Grafting

Flat grafting is a simple method of grafting that applies to all cacti species. The flat surface cut makes it easy to overlap the vascular rings of both pieces. There are two types of flat grafting: Columnar and Seedling Flat Grafting.

To do a flat columnar graft, sterilize the blade and simply make a straight flat slice across the top of the columnar rootstock, then chamfer the sides. In the same way, make a flat cut across the bottom of the scion. Attach quickly on top of the rootstock with overlapping vascular tissue. Secure the graft with a tape or rubber band.

A seedling graft is common with pereskiopsis spathulata cactus. To make a seedling graft, get a pereskiopsis cactus as a rootstock. Using the same technique, make a flat cut off the top of the pereskiopsis rootstock. Take a seedling and cut off the bottom as straight as possible. Join the two pieces with vascular rings overlapping and secure with plastic wraps.

Side Grafting

Side grafting uses the same method as flat grafting, but the position of the scion on the side of the rootstock. Side graft is usually used on Opuntia species rootstock.

Cleft or “V” type Grafting

Cleft or V-type grafting is another method wherein a rootstock is cut in a cleft or V type. The bottom cut of your scion has to be in the same manner as the rootstock. The rootstock and the scion must fit in securely.

Impale Grafting

This grafting technique applies to scions that are too large to be placed on top of the rootstock. To do an impale graft, use a sterile blade to sharpen the top of the rootstock but do not cut the core to the point that it will look like a blunt pencil. From the scion, make a circular cut wide enough for the rootstock to fit in. Stick the scion on top of the pointed rootstock and apply a little pressure—secure graft with a tape or a rubber band.

Areole Grafting

You can also graft cacti using its areole. Sometimes, valuable cacti die and leave only bits of their part like an aerole. So to save a piece, you can take an aerole and use it as a scion. You may use any rootstock compatible with the scion. With a sterile knife, cut the top of the rootstock and position your aerole on top. Fasten with a tape or rubber band.

Takeaways

  1. Grafting a mutant Gymnocalycium to any compatible rootstock will form a new plant called the moon cactus.
  2. It is important to note that cactus are susceptible to pathogens. So it is imperative to use sterile tools when handling and grafting.
  3. For a successful graft, it is vital to consider the compatibility of the scion and the rootstock.

Sources

“How to write a specific name,” Horticultural 202 Laboratory, Texas A & M University

“Cacti Grafting Stocks,” Kadas Garden

“Plant Cells, Tissues, and Tissue Systems,” Furman University

“Propagating Cacti With Aeroles,” by G.Krastinya, Riga, Latvia Republic

“Plant Grafting for Home Gardeners,” James E. Ells and Harrison G. Hughes, Colorado State University

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Esther

Esther is the self-proclaimed cactusholic :D of the team. She owns a cacti shop with hundreds of plants that she takes care of. Esther has many years of experience in growing and caring for drought-resistant plants like cacti and succulents.

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