Re: Rot epidemic

[Steve Johnson]

Sorry, but something got messed up in your thread, and for some weird reason it's not accepting new posts. So here's your last one:

I appreciate very much the detailed responses from ATP and Steve. I am soooo confused now about a proper substrate ]. It seems that when I was mixing added gravel, sand & perlite into soil from those 'standard' cactus potting soil bags, it was still too heavy and remained wet too long. Then I found this site and read all the 'ideal' potting soil recipes I could find and started using them. I asked about sterilizing soil and gravel in the micro or the oven and got mixed comments. Add to my confusion. Then coir seemed all the rage because it was fibrous and was supposed to keep just the right amount of moisture around the roots. I never used it exclusively but mixed it with pumice, which I gathered was a cure-all by all its fans in the Forum. I started that last year. It appears to have worked very well with some cacti, but now maybe not at all with others. Through all of my experimentation the advice about using NON-organic materials was an important theme to avoid decomposition, which leads to too acid a soil; but I understood that coir was the least likely to decompose to a risky stage. I just don't know what to do now.

So, Steve, I would be interested to know more about that 'Arizona Earth' if you can find out more. Very kind of you to suggest it. At this stage, should I consider any yellowing of the crown of a cactus a good sign that there is rot imminent?

I find it almost illogical that my outdoor cold-hardy cactus garden way up here in Vermont is more reliable and doing better that so much of my collection in the very expensive, custom-built greenhouse.

Any sudden changes on cacti are never good, and that would certainly be the case with yellowing at the crown. IMO coir and peat/sphagnum are the worst ingredients going into a mix for desert cacti, and they both have the same problem -- takes a long time to wet, but once the stuff gets saturated it takes forever to dry out. If I get a useful response from the Desert Earth Naturals people, I'll give you some feedback.