Help, received a small Totem Pole Cactus as a gift. I believed I have seen them growing outside in yards (Phoenix AZ area) so I set it out to get morning sun. The top turned a mushy black. It healed over quickly, but is now a dry hard black. New symptom, is it now has small black spots. Can it be saved?

to the forum!

I do not have any experience with the plant or the climate, but maybe one of our AZ natives might have some ideas for you. Paging @mcvansoest

If you put it outside in the full sun in the last couple of weeks then I am not surprised it responded with immediate sun burn. Not know its original growing conditions (light exposure etc) you want to be careful putting this out in the full summer sun.

Had it been any other time of year I think you would have not had this happen as I would normally consider these tanks able to take almost everything but significant below freezing temperatures.

I think the sunburn spot is not a huge concern, if the plant is actually rooted and based on the black spots I am a little worried that it may have poor roots atm. Do you know if it has good roots?
Assuming you have been watering it a bit the absence (or only limited presence) of roots might have had some adverse effects on the plant.

I think it is still OK. It overall looks solid still and if the black spots do not get bigger I am sure it will be fine. My advice: find an outside spot out of most sun. Keep it there. Do not water it for a while ( say 4-7 days) to see how the plant fares, then get a larger pot and some cactus soil and transplant it so you can inspect the root mass of the plant.

If the plant has good roots, you can resume limited watering say a week after repotting and then as long as it is hot give it say weekly to bi-weekly waterings. I have kept pieces of this unpotted for over a year then stuck them in a pot and they rooted and grew just fine. Hence my reference to them as a tank, but too much moisture is what will get them, if anything.

If the worst happens and this plant does not make it. I would be happy to replace it. I have plenty of rooted cuttings (a friend regularly has me come over to trim her giant monster totem pole cactus).

As to exposing it to more sun, once you have established your plant has roots you can post summer start exposing it to more sun by gradually putting it in spots that receive more ie. morning sun first, etc... They will take full sun here, but most that do are planted in the ground where they can spread there large root system around.

Then next summer it will like not suffer the severe sun stress your plant did, maybe some yellowing or on new growth or nothing at all.