Succulents, known for their specialized water-storing tissues, are unique candidates for the horticultural practice of grafting. Grafting involves joining a piece of one plant, the scion, onto the established root system of another plant, the rootstock, to create a single, unified organism. This technique is commonly employed, especially within the Cactaceae family, which makes up a significant portion of the succulent world. The process requires precision and an understanding of plant anatomy to ensure the two specimens successfully merge.
Possibility and Rationale for Grafting
Grafting succulents offers distinct advantages. One primary motivation is to significantly accelerate the growth rate of naturally slow-growing species, such as some cacti, by attaching them to a fast-growing rootstock. The established root system of the stock plant provides an immediate and robust supply of water and nutrients to the scion, bypassing the need for the scion to develop its own extensive root system first.
This technique is also essential for non-photosynthetic or mutated succulents that lack chlorophyll, like the vibrant “Moon Cactus” (Gymnocalycium mihanovichii). Since these plants cannot produce their own food, they are grafted onto a healthy, green rootstock, such as Hylocereus, which supplies all necessary energy for the scion’s survival. Furthermore, grafting can serve as a corrective measure, allowing growers to bypass issues like root rot or pest infestations by joining the healthy portion of a plant to a disease-free rootstock. A strong rootstock can also help maintain desirable variegation patterns in some delicate cultivars.
Preparation and Necessary Tools
The success of the graft begins with the careful selection of compatible plant material. The scion and rootstock should be from the same genus or closely related families to minimize the chance of rejection. Both plants should be turgid and in an active growth phase, typically during the warmer months. Dormant plants lack the necessary cell division activity for a successful union.
A sharp cutting instrument, such as a sterilized razor blade or scalpel, is required to ensure a clean, smooth cut without crushing the fleshy tissue. Sterilization is paramount and must be performed with 70% isopropyl alcohol on the blade before and between each cut to prevent the introduction of pathogens. Other necessary tools include non-latex rubber bands or string to secure the graft, and sometimes a small brush for cleaning debris from the cut surfaces.
Succulent Grafting Techniques
The most common technique for succulents is the flat graft, which involves making perfectly level horizontal cuts on both the rootstock and the scion. The goal is to maximize contact between the vascular bundles, which appear as a ring or core structure when the stem is cut. For the graft to succeed, the vascular rings of the scion and the rootstock must be aligned, ensuring the cambium layers—the thin, active growth tissue just beneath the skin—touch or significantly overlap.
Begin by making a precise, flat cut across the rootstock stem, typically a few inches above the soil line, and immediately follow with a matching cut on the scion. Working quickly is important to prevent the cut surfaces from drying out, which can inhibit fusion. After cutting, carefully bevel the edges of the rootstock cut by shaving off a small ring of tissue around the perimeter. This prevents the rootstock’s edge from drying and healing over the scion.
The scion is then placed directly on the rootstock, ensuring the vascular cores are at least partially aligned. Positioning the smaller scion core slightly off-center often guarantees overlap. Since succulent sap does not adhere the parts, the two pieces must be secured firmly together with gentle but consistent pressure. Rubber bands are typically looped around the bottom of the rootstock’s pot and stretched over the top of the scion to hold the union snug during healing.
Ensuring Successful Union and Care
After securing the scion and rootstock, they must be placed in an environment conducive to callus formation, which is the undifferentiated tissue that bridges the gap between the two plants. The graft requires a warm, protected area with bright, indirect light, avoiding direct sun which can scorch the fresh tissues. High humidity should be avoided, as surface moisture at the graft site can promote fungal or bacterial rot, a major cause of failure.
The graft should remain undisturbed for two to four weeks, allowing the tissues to fuse; watering must be withheld during this period. A successful union is indicated by the scion showing no signs of shriveling and, eventually, by the appearance of new growth. Securing materials, like rubber bands, can be removed once the union is firm, usually after ten days to three weeks.
Long-term maintenance involves monitoring the rootstock for any new growth, often called “pups” or offsets, emerging from its sides or top. These growths must be promptly trimmed off, as they compete with the scion for the rootstock’s energy and nutrient supply. Allowing the rootstock to focus all its resources on the scion ensures the continued vigor and successful growth of the grafted plant.