Question
My Argentine Giant Cactus has several arm and is about 5 foot across.  It produces many flowers at each blooming but I have noticed that the arms are starting to turn yellow... Is it getting to much water or not enough or is it something else causing the problem...

Answer
Dear Sharon,

I'm assuming by the size it's outdoors?  It's hard to say what's causing the yellowing.  No mushiness, black areas?  That would be rot tho it doesn't sound like that.  Other possibilities: 1. Sometimes older branches  become yellow because the plant is using it's energy for new growth. 2.  It needs fertilizer.  You can use a balanced 10-10-10 or fertilizer  specific to cacti which usually has a 1-2-2 ratio. 3. if it is in a pot it probably could use new soil (I know, you're saying "is she nuts?"). 4.  If outdoors you needn't water it at all if you get some rain.  If the soil gets totally dry, then drench it with water...overwatering will kill it.

If you send me a picture, that would help but I hope these possibilities will help.

maureen