Grafting Crested Cacti
*For more information also see our Cactus grafting guide* This guide is more like an extension to the Cacti grafting guide. If you are unfamiliar with the grafting process, we suggest you read the other guide first, as this guide plays off of that one.
Sterilize: Making something extremely clean and free from any bacteria/fungus etc.
Root stock: The cactus you will use on the bottom, that is being used with roots to help the other grow.
Scion: The cactus you will be placing on top of another, in hopes of increased growth.
The main reason for grafting cacti, is to get faster growth. Some species are incredibly slow (and rare) and grafting is a good way to propagate them faster. It is especially useful when trying to obtain seeds.
Because grafting increases growth so much, it may also make the cacti scion (top) grow funny or unlike a seed grown plant. Some rootstocks make the scion more "deformed" looking than others (Pereskiopsis is notorious for this).
Before grafting one must realize there is risk in doing this. You are, in fact, cutting your cactus in half. There is the risk of them getting infected, or making a bad join and having the scion, or worse, the scion and rootstock, die. Be sure you are willing to risk your plants, and be sure you are ready to try grafting. Stay clean and work fast and steady and things should be ok.
When all your materials are ready, it is time to make the first cut. You want to make sure that both the rootstock and scion are actively growing before grafting. First step is to cut the root stock. Cut it in a place that has grown this growing season, this will be softer juicier tissue...which is what you want. It is important to know that height is relatively unimportant. It is only useful to have taller stocks as that will absorb more light. Taller stocks, however, will pup much more and thus draw more energy away from the scion. What is really important is to choose a fast growing species, and have a fat base. The fatter the stock, the bigger and faster the scion will become (in general).
Because crested cacti generally grow in a fan type fashion, meaning the grow out sideways, the way we cut the scion will influence the way it will grow. You can cut the scion anyway you like and attach it, and it will grow, but here we want to influence the shape! With many crests, especially larger and slower growing species, the goal is indeed a fan shape (hand held fan). Crested cacti generally grow from both ends, and once they are stopped will eventually grow up and out.
Some examples of nicely formed "fan" shaped crests.
In order to accomplish nice form, generally one needs to cut the scion in a flat bottomed V shape. Such as: \_/ . When cut in this fashion, the scion crest will grow out at the ends at the top and grow out and down, creating the beginning of the crest. Again this is not mandatory, but is useful in obtaining those nice shaped crests alter on.
Take your crest and make a diagonal cut on both sides (wider at top, narrower at roots/bottom).
It will look something like this after. Now cut the bottom flat, this is what you will stick to the root stock.
With normal, often round, scions people often just make straight, flat cuts. And that works excellent! With crests the vascular bundles are arranged differently. When you look at a cross section of a normal round cactus, you will find the vascular tissues arranged in a ring more or less in the center. With crested cacti this is more elongated as the apical meristem is stretch sideways, and so the vascular system follows suite and grows elongated as well. The photos below show this.
Exceptions to the rule! Strictly stating that if the 2 vascular rings (root stocks and scions) don't line up, the graft will die is a bit of a myth. In fact this rarely happens due to the fact that there are many more vascular rings other than the big one in the center. There is also at minimum one bundle going to EVERY areole (where the spines are), usually more. As long as any of these areas are cut open and connected to another cut open one on the other plant, the graft will work, although generally grows slower than if connected well to the main ring in the center!
Here is a picture of an Ariocarpus fissuratus cut in half to show the vascular tissues, notice they dry out raised and harder? Keep that in mind when grafting. Other species are not so easy to tell.
Once the graft is taped together it is time to put it in a warm medium lit place. We often choose places that are dark and place a few fluorescent lights over top. We now keep ours in about 50%+ humidity for about a week (depends on species) then slowly acclimate them to drier conditions over 2-3 weeks before putting them with the rest of the cacti outside (or in your greenhouse/grow room).
When you first make your graft and tape it down you must keep it in lower light conditions and sometimes a little more humid. The goal is to slowly take them out of their protected environment and put them back outside.