Question
I bought a Myrtillocacus geometrizans crest "Dinosaur Back" cactus from the Desert Botanical Garden in Phoenix 2 years ago. It's been doing great - in fact a arm grew out of the grafted crest and in the 2 years I've had it, the arm grew to about 4-5" tall. However, its very thin and is starting to lean and just today I noticed that the crest is starting to shrivel. I'm distressed because I cant find cacti like this where I live (DFW, TX) and I've grown quite attached. Do you know why the crest would start to shrivel? The arm that's growing up off it is bright green, esp at the tip. I've noticed that whenever it grows it is this bright color, so I know that arm at least is healthy. Should I trim it off? Can the whole cactus be saved or at least part?

Answer
Coleen,

Sorry for the delay in getting back to you. Based on your description of the symptoms, it sounds like there may be 2 issues. The first is that it sounds like you have your plant indoors. For cacti, unless there is a lot of additional intense light. Do not put it in direct sunlight, because if it is not used to it, it will die.

It also could also be a lack of water. Try adding a product called "Superthrive" (available at most nurseries) to the water. Soak it really well, then don't water again until the soil is dry. Also, if your plant is indoors, position a grow lamp above it and make sure it gets at least 15 hours a day of light. Hopefully this helps.

Sincerely,

Greg