HELP my cactus, pot said balloon cactus, seems to be shriveling from the bottom and working up.
I have had this plant since July and it is in full sun on my courtyard.
I water once a month so I don't think it is too much water. I poked around the base and no sign of rot it still seemed firmly in the soil, but I did not dig it up.
Any chance it just needs more water? It made it through last summer in the same spot so I think the sun should be ok. Ideas??

How does the body itself feel?
Squishy? If squishy, it might still be rot - rot does not always get the roots first unfortunately....

Not sure if you are in Arizona, but I think you are, did the plant get any of the rain from a couple of weeks ago? If so, too little water would seem impossible, but it has been quite hot already for periods of time, so it could just be a little too little water.

I am already watering most of my potted plants that get a lot of sun once every two weeks, because they were looking like they needed it and then it rained of course...

It is Parodia magnifica and it looks like it is getting sunburned. Where do you live? Someplace it lives outside all year around? Or an enclosed patio? Mine live in a greenhouse and I water every two weeks in the winter and once a week in the summer. Maybe you are not watering enough.

My recommendation is to make sure it's planted in a medium that drains well and water more often.

Daisy

Thank you both. I am in the Phoenix area and hoping it is just need of water, as it was sheltered from the past rain. Will keep my fingers crossed. If it doesn't make it, any suggestions for a small cactus that can take full Phoenix area sun?

If it was sheltered from the past rain, then I agree with Daisy that it was probably just not quite enough water. The late winter/early spring here was generally speaking pretty warm, add the changing sun angle and stronger sun, and all of a sudden not getting enough water becomes a problem even for cacti. I'd up the watering frequency, but also make sure you have well draining soil like Daisy suggests, because you still do not want the plant to be wet too long.

These guys probably like a bit of shade in the hot summer months and once they have gotten used to a certain orientation to the sun you should maintain that, otherwise the newly exposed side of the cactus not used to the sun will sunburn quite badly.

I had this species in NY and gave mine a full soaking once a week in the summer and it thrived, yours looks like it needs more water to fill out.

Yea my cactus is back to normal. Nice and plump! It needed water. I gave it a good drink twice and all looks good now. It is still in full sun and looking good. Thanks for help!