A graft joins a piece of one cactus to the base of another so that the 2 grow as one plant. For Trichocereus collectors, it turns a small piece of a rare clone into more plants, sooner.
The short version
- A graft has 2 parts: the stock, the lower plant, which has roots or grows them, and the scion, the piece set on top. Rare Trichocereus clones are commonly grafted onto San Pedro (a Trichocereus).
- The 2 parts join when the rings of water-carrying tissue in their cut faces touch and are held firmly together while new tissue grows across.
- A graft gets more pups sooner from a rare clone, speeds up slow clones and seedlings, helps variegated, crested and monstrose forms grow and look their best, and saves the sound pieces of a broken column. For a single plant of a clone that roots easily, it is optional.
- On columns, collectors graft the tip, a puck (a short piece from the middle of a column) or a slab (a thinner slice), down to a slice with a single areole, one of the small pads that carry the spines.
- San Pedro is the most used grafting stock. Golden torch (Trichocereus spachianus) and blue myrtle are also used.
- The scion stays the same plant, though it may grow faster and look different on a graft. The stock wears out in time.
Stock and scion
The stock (or rootstock) supplies the roots and, once the graft has joined, takes up water and nutrients for the scion. The scion is the plant you want more of, often a piece of a rare clone; a clone is all the plants propagated from cuttings or pups of one original plant.
The stock can be a rooted plant or an unrooted cutting. An unrooted stock is cut about a week ahead and laid in shade with moving air so the cut end dries and hardens over (callusing), then grafted and rooted afterward. Give an unrooted cutting no water until it has rooted. Rooting takes 4 to 8 weeks.
Cacti with no chlorophyll, the green pigment a plant uses to make its food, cannot feed themselves and survive only as grafts on a green stock.
How the 2 parts join
Inside a cactus stem, the tissue that carries water and food runs in a ring between the outer flesh and the soft core. This is the vascular ring. Both plants are cut straight across, the scion is set on the stock so the 2 rings touch, and the 2 are held firmly together. New soft tissue, called callus, grows from the cut faces and bridges the gap, and cells in that bridge turn into vascular tissue that links the scion's ring to the stock's.
The rings have to touch but need not match in size. A scion and stock of similar width are centered. On a stock wider than the scion, growers set the scion off center so its ring lies across the stock's ring on one side.
When small seedling cacti were grafted onto a distantly related stock with the cut ends of the rings placed together, almost every graft had connected at 20 days. With the ring ends set 1 mm apart, 40% connected; at 3 mm apart, 10%.
A graft also needs:
- Fresh cut faces. A face that dries before the 2 pieces meet will not join, so the scion goes on as soon as the cuts are made.
- Firm, even pressure. Rubber bands or tape hold the scion down, generally for 1 to 2 weeks.
- Active growth. Both plants should be actively growing. Grafts made in spring tend to do better than grafts made in autumn.
- A clean blade. Cactus viruses can spread on grafting and cutting tools. Wipe off any sap and dirt, then wipe the blade with 70% isopropyl alcohol so it stays wet for at least 30 seconds. Let it air dry. Do this before each graft.
By the time the bands come off, a scion that has joined is starting to firm up and look plumper. One that is still soft at 2 weeks has probably not joined. Growers then cut both pieces back to fresh tissue and make the graft again.
Why collectors graft Trichocereus
For 1 plant of a clone that roots easily, growers usually root a cutting instead. Grafting pays off for these goals.
More pups, sooner, from a rare clone. A pup (also called an offset) is a side shoot that can be taken off and grown as a new plant. On a vigorous stock, a small piece of a rare clone can put out a good number of strong pups quickly. Collectors often set a slab or puck of the clone on San Pedro for this, then take each pup off and graft it in turn, so one scarce cutting becomes many plants.
Faster growth for slow clones and seedlings. A slow scion on a large, well-rooted stock generally grows faster than it would on its own roots. Seedling tops are often grafted onto a big stock for the same reason.
Variegated, crested and monstrose forms. A variegated plant has patches of yellow, cream or white where the stem has little or no chlorophyll. A crested plant has a growing point that has spread into a fan or ridge, and a monstrose plant makes irregular, lumpy growth from many points. Crested and monstrose forms are often grafted to keep them looking their best, and collectors find they pup more freely that way. A variegated pup taken off its mother tends to grow faster on a stock, though some variegated plants with green in them can grow on their own roots.
Saving a broken column. The sound pieces of a broken or crushed column, even a thin slice left at the base, can be grafted as slabs. Cut back until only healthy tissue with no brown or discolored patches remains.
The graft types used on columns
- Tip graft. The growing tip of the scion goes on the stock, so the clone keeps growing up from its own tip.
- Puck graft. A short, round section from the middle of a column. With no growing tip, it grows by pushing pups from its areoles.
- Slab graft. A thinner cross-section that also pups from its areoles. The smallest is the single-areole graft, a slice carrying 1 areole, which gets the most grafts from scarce material.
How thick to cut each type, where to cut the stock and how to fit the 2 together are in grafting onto San Pedro.
Which stocks are used
San Pedro is the stock growers reach for most often with Trichocereus. It grows vigorously, carries a wide scion and has small, sparse spines, so it is easy to handle. How long a San Pedro stock lasts varies; it generally outlasts other stocks, and every stock wears out in time. A failing stock may shrivel and not recover after watering, turn yellow, or soften below the join. The scion can then go onto a fresh stock or be rooted, as covered in caring for grafted cacti.
Golden torch (Trichocereus spachianus) is the next most common. It is spinier and harder to handle, and its stem tends to brown in patches, which cuts short its use as a stock.
Blue myrtle (Myrtillocactus geometrizans) is also used. Cacti can be grafted across distant relatives, so the stock does not have to be a Trichocereus.
What grafting changes and what it does not
A graft does not change the scion's genes, and its pups belong to the same clone. What can change is how it grows. Some growers find that a clone grows thicker and faster on a graft, with brighter spines, than on its own roots.
The stock keeps growing too and may push its own pups, which compete with the scion for nutrients and are removed as they appear.
Where to go next
- Choosing a stock: choosing grafting stock. A San Pedro mid-section sold as grafting stock is one option.
- Making the graft step by step: grafting onto San Pedro.
- Aftercare, stock pups and taking the scion off: caring for grafted cacti.
Sources
The Double-Cut Technique for Grafting Cacti to Trichocereus pachanoi Rootstock. Dan Bach, Desert Plants 3(1), 1981 (reprinted), University of Arizona. http://hdl.handle.net/10150/556561
Studies on Inter-generic Grafting Compatibility of Ornamental Cacti. R. Perumal, M. Prabhu, M. Kannan and S. Srinivasan, International Journal of Current Microbiology and Applied Sciences 9(11):2133-2144, 2020. https://www.ijcmas.com/9-11-2020/R.%20Perumal,%20et%20al.pdf
Does Grafting Time Affect the Cactus Performance? Neda Bayat, Roohangiz Naderi and Ardeshir Rahimi Maidani, Journal of Biological and Environmental Sciences 9(27):143-149, 2015. https://dergipark.org.tr/en/pub/jbes/article/1674713
Physiological Study of Graft Union Formation in Cactus: II. Role of Auxin on Vascular Connection between Stock and Scion. Takashi Shimomura and Kenzo Fuzihara, Journal of the Japanese Society for Horticultural Science 45(4):397-406, 1977. https://www.jstage.jst.go.jp/article/jjshs1925/45/4/45_4_397/_article
Grafting Types, Cactus Grafting. Plant Propagation, University of Florida IFAS, University of Kentucky and Texas A&M University, 2023. https://propg.ifas.ufl.edu/06-grafting/02-graftingtypes/05-grafting-cactus.html
Propagation (chapter 13). Extension Gardener Handbook, NC State Extension. https://content.ces.ncsu.edu/extension-gardener-handbook/13-propagation
A brief review of plant diseases caused by Cactus virus X. Edzel Evallo, John Darby Taguiam and Mark Angelo Balendres, Crop Protection, 2021. https://www.ukdr.uplb.edu.ph/journal-articles/32
Plant Disease Pointers, January 2022: Decontaminating Your Way to Healthier Plants. University of Wisconsin-Madison Plant Disease Diagnostics Clinic, 2022. https://pddc.wisc.edu/2022/01/27/january-2021-decontaminating-your-way-to-healthier-plants/
Clean and disinfect gardening tools and containers. Julie Weisenhorn, Natalie Hoidal and Annalisa Hultberg, University of Minnesota Extension, reviewed 2026. https://extension.umn.edu/planting-and-growing-guides/clean-and-disinfect-gardening-tools