Non-compressible in this context means the planting media particles are rigid in terms of size and shape. They do not shrink in size over the course of years. Gravel, for example, is non-compressible.
Compressible media can expand and contract. Think coir. Have you ever added water to a coir brick and seen how much it expands in volume? Loose media like peat and coir offer no resistance to root expansion. It goes hand-in-hand with decomposition, for as the organic material decomposes and the particle size gets smaller, it tends to pack tightly, staying really wet and excluding oxygen from the roots for extended periods of time when watered. This, of course is dangerous for rot-sensitive roots like Adenium.
The problem I have with the "non-compressible" media, with large particle size (1/8"+) that the author recommends, is that it will dry out too quickly.
I also am in south Florida. In our rainy season (which we are just now entering) it rains most every day and humidity is high (therefore evaporation is low), and during this time of year his media likely works wonderfully. However, during our fall and spring, when it still gets hot during the day and stays warm at night, the warm, dry wind tends to suck the moisture out of everything, especially in the sun, including "organic, compressible" media. Open media like he suggests would dry out in a few hours and would need to be watered at least twice per day.
Perhaps the author has his Adenium on an automatic watering system, or he is retired and has plenty of time on his hands to water his Adeniums. For me, I have problems with plants in soil in 1-gal containers on workdays when I can only water once. On my days off, I water when I get up in the morning, then again in early evening.
OK. Let me play devil's advocate against myself. I have not actually (yet) tried his media. Perhaps the organic materials tend to wick the moisture up as the surface dries, and so dries out the whole pot. Perhaps his moisture-absorbing clay will hold moisture better than moisture-retentive soil against the sun and the hot, dry wind. I don't know. I'll concede I may be wrong in my assumptions above, so will be interested to hear how it works for others under different climate conditions, as well as experimenting for myself.
I do take issue with a couple of his photos
He emphasizes
non-clumping cat litter, yet the photo he shows is clearly marked "Bentonite Cat Litter", which is the clumping kind,
NOT the type litter you should be looking for.
Charcoal is not light grey, it is very, very black. Almost black-hole black. I recognize the material shown as aquarium filter media, possibly another variety of zeolite.
I'm also not sure about his plant-growth aquarium gravel. Be sure to note the particle size if you are looking for this. The type I'm familiar with that has the larger particle size he recommends tend to an overall dark red-brown color, not black. The black type is more sandy with a high percentage of small particles.
I'll get off my soap-box now.
Overall, this article is very good and I am certainly not trying to discredit the author. It needs to be widely read and considered by anyone serious about potted Adeniums. Dave Bogert provides us with a lot of good information, and does a wonderful job helping us to think in new ways about growing our Adeniums. So still,
to him!
I'm just offering a couple thoughts, my 2ยข worth.
