Question
Dear Greg,

The upper 6 to 8 inches on my cactus is turning a dark purple to black.  Is this an indication of root rot and if so, what do I need to do to fix it?  Please advise.  Thank you.

Mark

Answer
Mark,

Generally root rot starts from the bottom of the plant. I need to ask you a question, is your plant outside? If it is, then your probably dealing with frost damage (the damage would have occured a few weeks back). If that is the case, your plant looks like most of mine right now.

You can remove the damaged part and the plant should branch from just below the cut. If your plant is inside, it may be root rot or just a lack of water. cacti should be watered when the soil dries, and not a teaspoon. Soak the soil good, then let it dry out, then soak again. This cycle might take a month or more.

Hope this helps.

Sincerely,

Greg