My Cereus Cactus Is Turning Yellow From Bottom Up, Is It Dying, What Can I Do To Save It?

Question

it is planted outside, east facing in front of house in the anza borrego desert there is another planted across from it doing just fine nice and green.

Answer 1

Unfortunately, your photo did not come through. I am unable to see the damage.

There are several things that can cause yellowing. My first suspect is overwatering. This can cause root rotting, which can cause the symptoms that you are seeing.

Next will be a lack of sun. They need as much as possible, and planted on the East side of a structure can cause enough shade for it to be unhappy.

This article will help you to know what care these plants require:

https://www.gardeningknowhow.com/ornamental/cacti-succulents/night-blooming-cereus/night-blooming-cereus.htm