Vinegar and cactus...is this true?
Tap water is hard on cactus plants and will gradually cause them to stop growing, and more and more growers are using white vinegar to modify tap water for healthier cactus plants. There is a great article on this subject in the September through October 2008 issue of the Cactus and Succulent Journal put out by the CSSA, The Cactus and Succulent Society of America. We never use tap water on any cactus plant, but this is surely important enough to write about on this web page. The recommended amount in the Cactus and Succulent Journal of white vinegar to modify tap water is one table spoon for five gallons of water. By my math for smaller amounts use 9 drops of white vinegar in one quart of tap water or .26 cc of white vinegar in one litre of tap water and the water will be safer to use on cacti. If it is unavoidable to use tap water it can be modified with white vinegar, and that will help keep cactus plants healthy. Rain water or distilled water will be better than tap water, but if tap water has to be used it is better to modify it with white vinegar. Water modified with white vinegar needs to be used or disposed of the same day it is mixed because it will spoil if stored.
I always let the water sit at least 24 hours, most often longer before watering. I just read this tonight and hadn't heard of it before and want to see what you all think of this?
Here is a link that might be useful: Windowsill Cactus Growing Information link