Cacti (Cactaceae plant family) are slow-growing succulents with well-developed vascular systems, or systems that transport food and water through the system. Thanks to this system, if a piece breaks off the cactus, you may have several different options to salvage it. This may mean grafting, but it can also mean planting the damaged piece as a new specimen. There are a number of things to consider when evaluating a broken cactus to see if it can be saved.
It may be possible to save a broken cactus via grafting or planting the broken-off piece as a new plant.
Grafting a Damaged Cactus Piece
Broken pieces often have jagged edges and damaged tissues, so if you were to simply put the broken piece back onto the cactus and bind it in place, the chances for success are fairly low. If the wounded end on the broken piece and the stub were cut evenly with a sharp knife and you bound the broken piece into place on the stub, the chances of the cactus healing are much greater. This is because of the ease of grafting cactus plants and the very high probability of cacti of the same species grafting successfully. Alternately, you may be able to graft the broken piece onto another cactus, preferably of the same species.
Planting Cactus Pieces
Another possible way to salvage the damaged cactus is to plant the broken pieces in sand or a succulent potting mix until they root, which creates new cactus plants. It is best, however, to let the broken piece scab over for a few days in a warm, dry area with good circulation to prevent problems with fungal disease entering along the broken edge. Alternately, you may dip the broken edge in an anti-fungal sulfur solution. If the piece broke off because of disease or infection of the main plant, remove the diseased parts with a sharp, disinfected knife first, or the disease will claim the broken piece as well.
Evaluating the Aesthetics
Grafting leaves scars. This isn't a big problem if you have a sectioned cactus and it was a whole section that broke off. For many cacti, however, a broken section grafted back into place looks wounded, even if the graft heals.
It may be better to trim the stub back to a section further down or closer to the main section of the cactus, depending on the type of cactus, and then reattach the broken piece. If you will plant the broken piece for a new cactus or simply dispose of it altogether, it helps to trim the cactus, if possible, to remove jagged edges or odd-looking stumps. This factor may make a difference if you're concerned about the aesthetics of the plant.
Overall Healing Considerations
If the broken area is next to or on the base of the cactus, it is usually easier to simply allow the broken cactus piece to scab over and then replant it rather than try to get a graft to take. The wound is susceptible to fungal infection, especially if the soil is moist or comes into contact with the grafting joint. This is another factor to consider when trying to decide how to address a damaged area of the cactus.
Samantha Belyeu has been writing professionally since 2003. She began as a writer and publisher for the Natural Toxins Research Center and has spent her time since as a landscape designer and part-time writer. She holds a Bachelor of Arts in English from Texas A&M University in Kingsville.