Question
Picture of cactus
My young daughter purchased a cactus about a year ago. It came with a tag listing it as a "Gymnocalycium mihanovichii". The top colored part has died. I now understand that this was the moon cactus and was grafted on the other cactus. From looking online I think the cactus is a Hylocereus, correct me if I am wrong. About the time I was getting ready to throw it away (I did not know it was two different plants at the time) I noticed a new growth that has grown quickly (as you can see from the picture). I was wondering what if anything I need to do with the dead part and is there anything else I need to do with this cactus and the new arm growth. Also, it has these root looking things growing out of the new arm. Is there anything I need to do with them? This is a indoor plant. I water about every 10 days. Is this to much? The soil is so dry and we live in a very dry climate in Wyoming. Is there any kind of plant food I should use, as you can tell I do not know much about these cactuses. Thank You.
AnswerYes, I agree that the base is a hylocactus. Moon cactus cannot live on their own as they have no chlorophyll so are grafted onto another cactus. That is also why they have their amazing colors. My understanding is that even the best grafts only last a few years, as the base grows faster than the Gymnocalycium. After that point, the difference in speed between the two becomes too great for the graft to hold together, and the two split apart. I do, however believe longevity depends on the plants used and their care.
There are a few things you can do. You can slice off the old graft and brush the hylo with fungicide or rooting powder to prevent disease till it calluses. Hylocacti are epiphytes, or jungle cactus. The roots you see are normal. In habitat they cling to the trees and vines and absorb moisture that way, much like orchids. If you leave it as a single plant, it will put out more leaves and eventually bloom. The blooms are beautiful. It would have to be repotted in a more humusy soil as they are unlike other cacti as that they don't like to totally dry out, nor do they like bright, direct sun. They do better with an African violet soil mix with added perlite.
2nd: You could cut the leaf off and start another plant. The original will always have that flat top, but eventually new leaves will obscure it, but if you didn't like the look at least you'd have another plant started.
3rd: you could try another graft, either of that scion or another plant. A nice site with pictures is keinhong.tripod.com/grafting.html. My understanding is that hylo, while frequently used, isn't the strongest sicon. Your daughter might enjoy trying another graft with two other cactus and this site gives good directions.
Gymnocalyciums are nice plants. They stay small and are a bit different than most cacti as they don't like direct sun and need some water in the winter. They also flower easily and except for the chlorophyll free plants made specifically for grafting, grow quite well on their own and have some interesting shades.
So, you have a scion that you can decide what you want to do with, a leaf that you can start a new plant with, and/or try a new graft. If you do the last, get healthy but not expensive plants of the same species and preferably class. It's a skill, so expect some failures. This is a good time of year to try it anyway.
Good luck,
Maureen
Thanks for the photo.
