Question
I have a 4 foot specimen that lives in the house in the winter and on my patio in the summer.  I suspect the bottom 1/2 of the plant got sunburned several years ago as one side has a light brown plaque, is slightly bent and not as thick around.  The top portion is healthy.  The plant is top heavy and can't stand unaided.  Can I cut the top off and re-root it?   If so, how?  Thanks so much for any advice! I live in Denver.

Answer
Dear Tom.

Yes, you can.  Get a sharp knife, sterilize it with rubbing alcohol and cut above the sunburned area.  Let the cutting callous over for a couple of weeks till the cut end feels like cork (ish).  Then get a pot not much wider than the plant but deep enough to hold  it up.  I put mine in sifted builders sand. Plant it just deep enough so that it stays upright.  I moisten the sand and only give is some water again when it's dried out completely.  it can take weeks to months for a cactus to root so keep it in bright but not direct sunlight.  You will know it is rooted by new growth at the top and then you can put it in cactus soil. You can actually start it in cactus soil, I just don't have much luck doing it that way.

You can also see what happens with the bottom of the original plant.  If you can cut the sunburned, weak portion off, put the stub with roots in a smaller pot.  It may sprout arms.  You can never have too many totem poles.

Seriously, please let me know if you need more information, and good luck.  This is a good time  of year to root cacti.

Maureen