CactiGuide.com

Hello friends,

Nice to meet you all. I'm very new here.

I have a problem with my Cereus peruvianus (I think, please correct me if I'm wrong).

I accidentally over-watered it and the root rotted really bad, so yesterday I tried to cut the rotten part and left it out to dry. Today I found out that the root has turned white and black, as you can see in these photos.

The part that turns yellow still quite firm when I touch so I don't know what to do. What do you think should I do next? Should I leave it there or cut it too?

And is there anything else that I can do to save my cactus?

I am willing to do anything that I can since this is my sister's gift to me. I love them so much and I don't want them to go away.

I can't find any post that is similar to my situation for now so I make this post. Please feel free to correct me if I say anything wrong.

Thank you so much for your time. If you need more info please let me know.

I hope you have a wonderful day,

Cuz

You have to cut more till you only see green on the cut surface. Sterilize the knife between cuts. Some of the branches will detach. You could try to root them too.

As far as ID, better photos will help. Show the side and top of your plant.

I think it's Cereus (Acanthocereus) tetragonus cv Fairy Castle f. variegata.
Agreed with Jerry, you have to cut more off. The mostly green branches should be fine to root, but the more yellowish will take much longer or might not survive.

I think it's a plain fairy castle. It doesn't look variegated (to me).

Wow!! I can't believe that I can get so many replies so instantly. Thank you so much Jerry, Bryan and Evan for your kindest help! You guys really made my day a lot happier.

I will try every advice that you all just gave me and update how things going right away.

Here are some more photos that I just took that show the side and the top of the plant as Jerry advised me. Any more suggestion on what else I should do would be very very appreciated .

It is looking like you are keeping your cactus in a spot that is not getting enough light. The tip of each branch is elongated and very narrow. Also, are you using any fertilizer? Plants need to eat too!!

Yes. The plant is etiolated. I suspect this is a combination of too little light, and too much water. I understand that Vietnam has a monsoon season, which may have been the cause.

Thank you so much for getting back to me, Jerry and Evan. It really, truly means a lot.

Yes now is the rainy season here in my place so it's hard to get enough sunlight all the time. I manage to bring them out to the sun this morning but it still doesn't help much. The tip's even more wrinkled, elongated and getting softer (I think because it's too sunny and I forgot to bring them in at noon ). What do you think should I do with that part? Should I cut or just leave it there?

I also did use some smart fertilizer for cactus called Osmocote right before my cactus's getting rotten but maybe I wasn't using it enough. Was this one a good choice for my cactus?

Here are some pictures I took so that it will be much clearer for you to imagine.

Hi, it's Cereus peruvianus "Paolina" = dwarf "Fairy Castle", not Acanthocereus.
Hope it will root successfully and will grow happily somewhere in the sun without overwatering.

You might want to invest in a LED spotlight to give it extra light during cloudy days. You have to acclimate plants to increases in light or they will sunburn.

Elongated, etiolated growth will not correct itself. If you cut off the tips you will have a deformed cactus and it might pup at the cut. Long term multi year recovery plan as I see it: root a few of your cuts. Grow under much higher light and dial in the fertilizing. Let your cuttings produce proper looking branches. Cut off good looking branches and root them.

Now you have a plant that looks like it should-and you have learned a lot about growing/cultivating cactus. Now you can go out and increase your collection since you have caught the bug.

This is a dwarf, monstrose cultivar - meaning it produces an extreme number of branches normally. In this case the form may not be that much different a couple years after pruning off those elongated tips than it would have been without the pruning (and you should prune them off, Jerry is correct that they won't correct themselves). Not a bad Idea to root some undeformed branches anyway, but you may find the difference is small.