Question
I got a grafted cactus plant during the summer.  In the pot there is three separate grafted cacti.  I recently noticed that the smallest of the three is starting to shrivel up (both the top and the bottom of the graft), turn a darker color, and feel mushy.  I have only watered the plant once since I got it.  When I noticed the change in the one cacti I checked if it needed watered and the soil was dry all the way through.  I was just wondering if this could be a sign of needing watered or if it is rotting.  Any help you could give would be great.

Answer
Renee,

It could be a sign of that or exposure to cold. Generally you want to water when the soil is dry (once a month or so). If the roots die on the root stock (the lower plant) then the whole plant will die. Cacti will require less water in the winter, but still need some moisture.

Sorry to hear about your plant, but hopefully the others will survive.

Sincerely,

Greg