Rotting mammillaria

This little cactus with spines the texture of steel wool (Mammillaria camptotricha cv. marnier-lapostollei) was one of my favorite purchases last summer. It bloomed almost right away and in general appeared to do well throughout the winter. It had been kept completely dry just like all the other cacti in my budding collection until I removed the covers in late February.

Mammillaria camptotricha cv. marnier-lapostollei

The other day I was moving pots around and bumped into this little guy. I noticed right away something was wrong when its body practically toppled over. Not a good sign!

I gently lifted it up with bare fingers (the spines are wiry but not sharp) and saw this:


Sure looks like rot to me. The soil was a little damp—some rain must have hit it in recent weeks after I removed the tarp. I would never have thought that just a splash of water could cause rot but in hindsight it was probably a combination of moisture and unseasonably cool temperatures with nighttime lows still in the 40s.


Ordinarily I would declare a cactus with so much rot a goner but I noticed fresh roots emerging from the side of the gaping hole:


Is there still hope? I decided to err on the side of optimism and placed the cactus on top of a small pot filled with completely dry soil mix high in pumice. Time will tell if it is a survivor or not.

In addition, I removed these two babies from the side of the cactus. The larger green one should survive just fine, the other one may or may not. But ultimately each failure is a valuable learning experience.



  1. Always sad to loose a plant over winter, but at least there are some signs of recovery and the offset as a replacement. fingers crossed everything survives but as you say each loss provides new information.

    1. To be honest, I would hate it if everything I did was a success. On the other hand, if this had been an expensive plant, I'd be thinking differently :-).

  2. I'm always hard on myself with my plant failures. My friend says hey, your doing just fine, considering you have a small army of them in and outside the house. As plant geeks we'll surely kill a plant or two, but I would still say the success rate is over 90%. Pat yourself on the back for a job well done, keeper. of. the. plants.


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