I don’t have a crystal ball so really couldn’t tell you how big it’ll get in 4-5 yrs, but I was always under the impression grafted plants grew quicker. I’m really surprised that your Cephalocereus was even grafted these grow fine on their own roots. Maybe the person really enjoys grafting;).

If you let the Cephalocereus grow a little you could detach during the growing season and reroot as a cutting. That’ll slow it down because it’ll grow roots first before top growth. Definitely let it gain some size first because your propagation will have a better chance.

They do get spines, but not like Oreocereus trollii aka Old Man of the Andes cactus those spines are pretty vicious.

Thanks Kara for your information. You are spot on as to why these two plants are grafted together. The vendor loves grafting and if you stand still long enough he will probably graft you as well........I guess we will just have to see how tall this will get. I don't want tall. Can't handle tall. But as my C&S must be able to survive overwinter inside the house, I know from past experience that only the most forgiving can handle inside conditions. So this may not be a problem after all...............Maryl

Cephalocereus senilis is a considered among the tallest and largest growing cacti, attributed to its relation to carnegiea, pachycereus, neoraimondia.

Since the graft is successful , you wont have to worry about compatibility problems(like saguaro) and as long you maintain the roots you should be fine.

However, if you ask how tall will your plant be, i ill have to point out that your plant is crested and that doesnt contribute to the height or speed department

Cephalocereus senilis isnt a fast grower, so there wont be drastic speed change like small cacti. Thats of course, if the plant was normal, not crested.

Spanish Fly; I can understand what you are saying about the technical necessity of grafting or not, but since I only dabble in C&S I go mainly for the looks of a plant. I found this hairy looking top combined with a non hairy bottom interesting looking. I was surprised to find out it was an Old Man Cactus after I brought it home and read about it as I'd seen them before and they didn't look like this wiry, bristly fluffed out "beard". They were taller, neatly fuzzed (with sharp spines if you looked carefully) and grew straight up.....Stephan, I know this vendor likes "crested" plants from some of his other plants for sale, so maybe this Old Man's Beard is crested??? I asked him how tall it would grow and he said the top would grow out not up. This grower wasn't very talkative so I didn't press him as I didn't even know then what the heck I'd bought. I just liked it. So, looking at it do you think it might be a "crested" Cepholocerus Sinilis? Is there such an animal?............Maryl

Now well now that makes more sense why he grafted it because it’s crested. The fact that the vendor said it’ll grow out instead of up is proof that’s it’s crested. Idk why he didn’t just tell you it was crested to begin with.

Yes crested versions do exist.

Pic from the Australian Cactus Forum

Pic from the internet to show you what it looks like on it’s own roots.

Spanishfly- I agree when I repotted my old Ariocarpus the taproot was really interesting and beautiful. The base of the cactus was so thick. I was worried it wasn’t gonna bud up, but I think I feel some buds forming. I’ll know in a couple weeks.

Maryl, im not giving you a maybe. IT IS crested. Almost cactus plants, have distinct way of showing off their new spines near their growth center. In the case of yours ,

http://plantsrescue.com/wp-content/uploads/2013/12/Cephalocereus-senilis-5.jpg

Youll notice that the new hairs are denser and somewhat spiral near the tip of the plant. Your plant doesnt possess that "tip", rather the new spines are spread out on the crests ridge.

Just to compare, parodia leninghuasii (and other eriocactus group relatives) have their darker new spines densely concentrated on the tip, forming a cone:

http://www.cactus-art.biz/schede/NOTOCACTUS/Notocactus_leninghausii/Notocactus_leninghausii/Notocactus_leninghausii.htm

Stefan: I am relieved to know that it is definitely crested and will not grow through my roof if it lives. I appreciate the links you supplied. Would I be right (simply put) to think that "cresting" is an aberration on a normal growing cactus and, for instance, can't be started any other way then by offsets?............Kara: I'm assuming that my vendor didn't say crested right off the bat because he didn't want to talk to another idiot buyer who might not know what "crested" means and then spend time explaining it (see question I asked above-lol). As I said, he wasn't very talkative. Hey, thanks for the pictures! I grow lots of herbacious plants but only a small amount of C&S due to space constraints and so appreciate people who take the time to answer my questions.........Maryl