Roots turning brown when entering leca

[Ale_V]

Good morning everyone,

I have had a Cattleya in S/H for months (repotted after it finished blooming), but I feel like something is not quite right.

The roots seem to be growing properly (outside the pot), but the few that have made their way into the LECA substrate don't seem to be doing well: some appear to be dying, with their tips turning black, while others continue to grow but not in an ideal way.

On the other hand, the aerial roots seem to be thriving. I’d say that in the four months it has been in S/H, aside from the roots, the plant hasn’t grown a single millimeter.

I water once a week with 1/4 of the recommended dose of Rain Mix in RO water.
Temperature: 25°C during the day, 21°C at night.
Humidity: between 90% and 80%.

Thanks a lot for any advice!


Ale

PS: I've taken the plant to the window to take some pictures but it lives inside a greenhouse with artificial light.

[Ray]

My guess is that one or two things are involved.

The damaged root tip suggests the LECA is either too dry and is desiccation the root tip when it makes contact, and/or has either not been properly cleaned, or has accumulated some salts or the like, that are toxic.

The fact that the one photo show a submerged root, deep in the pot, growing nicely, suggests the problem is localized to the surface.

[Grawski]

Ale V: I suspect that the Leca has a high salt content. My research led me to understand how Leca must be soaked with RO water to remove existing salts, then soaked again with a Epsom Salt and CalMag solution. Ray will have a clearer explanation of why this is done, but it affects the Leca's pH. I have saved an article on how this is done. I will search for it, then post it here.