Question
Hi there,

 I have a cactus that was given to me about 4 months ago and was healthy at the time. It is round, green,and has a organe top blossum. It is beginning to rot from the bottom. The roots seem fine but the base of the plant is becoming mushy from the inside. I have seen no sign of mold or anything else. I do not water it often, maybe once every 2-3 weeks and when I first recied the plant I put in in soil designed for cacti.  I have 6 other cacti that recieve similar treatment and are all healthy. The plant gets noderate light from a skylight but is not near a window. I just transplanted it in hope to do something to help it. Can you offer any advise? Thanks for the help.

Answer
Pearlie,

Rot at the bottom on cacti indicates too much water. In the winter it doesn't rain in some deserts, others it rains a lot. This plant comes from one of the drier ones so you should water very very little. As littl as once a month or just a few drops every week. I would reccommend moving it to a sunnier location also. Stop watering it completely until it starts looking better. Good luck.

Good luck.
Darlene