i just wrote this up for a guy and thought it may be useful here. let me know if you have any suggestions
In this pictorial i am using Myrtillocactus geometrizans (a favorite of mine) as the root stock and Trichocereus huascha f. cristate as the scion.
Whenever you are cutting your cactus, be sure to clean your blade. we use 95% Ethanol alcohol on a tissue to wipe the blade. allow a few seconds for the alcohol to evaporate.....and be safe with alcohol blah blah blah.
1) Take your crested cactus out of the pot and clear away most of its substrate. Put it aside so that its ready to cut later on.
2) Take your root stock and cut it where it is actuvely growing (this eyars growth). You do not want old growth because the vascular ring will be "woody" and not as easy to heal with a scion...thus very slow scion growth! So cut the top off where it is actively growing.
3) Bevel the ribs. When teh cactus is healing/drying the inner flesh is basically an open wound...so will dehydrate lots. the skin, which is well adapted to stay resilliant in dark times will not shrink and become a hard stiff "wall". So teh inner flesh shrinks, adn teh out skin doesn't...this is going to make the scion and the stock separate. So cut done the ribs. This also prevent sthe stock from sending out offests as many cacti will pup from the top (myrtles for example). If using T. pachanoi, for example, it will likely pup from the bottom but you should still bevel the ribs)
4) Now all the ribs are cut down on an angle. Cut a thin slice, a few mm thick, off the top and leave it on the top. This is done because when you are busy cutting the crested scion, the rootstock will begin to dry...that is bad. This way, when you are done mucking around with the scion and it is ready, you can simply, and quickly, pop off the top and it is fresh juicy flesh waiting to be grafted.
5) Now its time to move over to your scion. Crested cacti can be grafted like anything else....but the idea with most people is to get a "fan" appearance.
start by cutting your crest chunk that is to be grafted.
here is what the side section looks like. see the the vascular tissue going from the roots to the skin? just like regular cacti, but when you see a cross section it follows the crest shape rather than a circle like in regular forms....almost Opuntia like.
6) Now cut your scion chunk into a V shap, the top out skin bing the wider part and down by the roots being narrow.
7) Procede by cutting the V's bottom (roots) off flat. This should look like this: \__/
This is done to give you that nice fan shape. Will explain later.
Notice the vascular tissue in here...notice it is following the crest, as in going legnthwise the way the cactus is growing. that is what you need to connect with the vascualr RING on your root stock plant, its actually quite easy as you are lining up 2 lines on a circle, unlike 2 "normal" cacti you have to line up 2 circles...
It will also help to cut the edge of the skin along the botton of the scion...just like the bevel on the stock. i didn't here and often dont....but it helps if you remember!
now that its all cut take that slice off your root stock and place the scion on top of it. Like so.
9) Press down a little bit to make sure it connects ok.
10) Place some clean tissue on top.
11) using vinyl or eletrical tape (this is good cause it is stretchy...dont use masking tape, packing tape etc its not as good and goes loose....your want it to stay tight) tape over the scion and stick the tape to the cactus. not the pot, the cactus...this keeps it MUCH more secure. if it is taped to the sides of the pot the cactus stock can easily shake when the pot is moved, which rubs/jolts the scion...not good. i learned my lesson...tape it to the stock.
12) tape around the tape on the stock. this eeps the tape from unsticking....a loose tape job is a pointless tape job.
13) all done.
14) After abotu 1 week, carefully remove teh tape and keep in a somehwat humid environment. low light is ok. i keep them on my coffee table for another week after the tape is off then place them by a window for another week. after that, if the cuts are well healed, they go outside in partial sun, then to full sun
here it is finished about 3 weeks after and out in the sunshine
Ok now for the reason we cut the scion into a \__/ shape.
Crested cacti grow out from their "crack" . they will grow sideways, not up. so when you cut your crest like this \__/ when they start to grow they will grow out liek this *\__/* and gro outwards from teh sides eventually growing downwards and "pinching" the stock. this gives a very nice fan shape is is usually more desireable.
examples of fan shapes:
Stephen Robert Irwin: 22 February 1962 – 4 September 2006. Rest In Peace.