Question

Disscoloration   QUESTION: Hi Joan,

It's me again.  The growth on my moon cactus is pale green (which you say is normal so thats okay), but the whole upper half of each of the three stalks shows discoloration right up the center of each stalk.  I attached a picture and circled exactly what I am referring to!

Again thank you in advance for your time Joan!  I appreciate it.

Justin

ANSWER: Hello Justin,
It looks like those spots were burned in someway. You mentioned you use artificial light, right? If it was exposed to light heat (like the sun) then that is what probably caused it. A cactus should be adapted slowly to exposure of the sun to prevent this burn. I have only experienced this discoloration for that reason. Again, it isn't the lack of water (I have to keep repeating this to all the questioners). So don't overwater. Let me know if your plant was exposed to heat.

---------- FOLLOW-UP ----------

QUESTION: Hi Joan,

Yes the light does produce heat.  It is not super intense but it is quite noticable.  Originally the light was about 12 inches away from the cacti.  After my grafted cacti started to change colors I moved the light away by about another foot.  So do you think the heat produced by the light is the reason for the disscoloration?  Can the cacti survive these "burns"?

Thanks Joan!

Justin

ANSWER: Hello Justin,
It wasn't the heat that caused discoloration. It was because the cactus wasn't adapted to it. I was assuming that you got your cacti recently. If you had the cactus for more than a year under its current conditions, and the burns didn't become noticeable until now, than it wasn't the heat that caused this. So let me know if this is the case.

You did the right thing to do with removing the light a couple inches away. Put your hand over the cactus to see if your hand gets warm. If it does, move it back a couple inches more. As time passes, gradually move the light closer, that way the cactus would re-adapt to its environment. Since I believe this is a house plant, don't let the light too close that if you put your arms over the cactus, you would feel it too hot.

Soon, your cactus should experience no discoloration, and if its lucky, then you may expect new growth by spring.

---------- FOLLOW-UP ----------

QUESTION: Hi Joan!

I have actually had the cactus for about half a year now.  I only recently
bought the light though (within 30 days).  So hopefully it was just the shock
from the heat that caused this.  Will the disscoloration go away over time?  
Should I remove it from the light completely or will doing that only cause
more and more shock to the cacti?

Again thank you so much Joan!

Justin


Answer
Hello Justin,
So it probably was the light that caused it. I don't think the spots will recover completely. What I mean by that is that the plant burns won't go unnoticable over time. What you want to expect is new growth. If your plant will be unfortunate, I'm afraid your plant will slowy dry out and die. Otherwise, the plant will survive the burns and will just heal normally. But don't worry. They aren't that bad. With proper treatment I mentioned earlier, the plant will recover.

Also, don't remove the light. Do what I mentioned earlier :)