Nearly lost two crassulas to root rot (?)

[JonW]

I don't have any issue with my Crassula Ovata or Portulacaria Afra dropping leaves due to climate change anymore than the normal rate of retiring old leaves.

I'm surprised no one is talking about the soil. What is it planted in? You see people killing jades all the time in houseplant forums because they plant them in potting mixture. I keep mine in bonsai soil, currently mostly pumice. I'd think that makes much more difference than humidity - mine do fine on summer days with high humidity or in my house in fall before the humidity drops (which was most of the winter this year).

 

[luvinthemountains]

I'm surprised no one is talking about the soil. What is it planted in?

Both of these c. ovata are planted in a fine (~1/8") mix of 70% DE, 20% lava and 10% fir bark. In retrospect, a much higher ratio of lava (or pumice) might have been better. The DE does retain a bit more moisture.

 

[Carol 83]

The DE does retain a bit more moisture.

Yep. I had a bougie in DE, stayed far too wet for too long. I use Cactus/succulent soil for all my jades and p.afras. Works fine.

 

[JonW]

Both of these c. ovata are planted in a fine (~1/8") mix of 70% DE, 20% lava and 10% fir bark. In retrospect, a much higher ratio of lava (or pumice) might have been better. The DE does retain a bit more moisture.

I've used mixes like this and I've started ditching a lot of components personally. Not to start a soil war, but...

• DE/Turface: pros are that it has a great CEC, good for aeration, holds water for plants that like it, cheap. Cons it can hold more water than you want, other more porous rather than absorbent media has better O2 exchange and doesn't hold as much water, and you can improve CEC of other soil with humic acid anyway.
• Lava: good aeration/drainage, but I don't find it does much for roots that pumice doesn't do better.
• Bark: either won't absorb water if too dry or holds too much as it breaks down.
• Granite Grit: while it doesn't hold water, its surfaces let water pool on top of it, which displaces air a well. Surprisingly one of the worst offenders in terms of inorganic media for causing issues of too much water retention. This is a reason people mix it with bark: it pools water that bark can slowly absorb. If you use it, I'd advise tilting the pot back and forth after watering to get rid of excess water, but granite doesn't add anything that pumice doesn't seem to do better.
• Akadama: breaks down, but it has good aeration and drainage. Maybe better than pumice for refinement. I'm using 1/8th inch pumice for finer roots / smaller trees.

 

[luvinthemountains]

I use Cactus/succulent soil

The bagged mixes that I have been able to find are okay, but have too much peat in the mix, giving them the unfortunate quality of repelling water when dry. The plants that I have in it get watered by immersion to avoid dry zones in the root ball.

I now have 120lbs of pumice on-hand, which will no doubt improve my mixes.