Yellowing leaves on Monstera, Philodendron, Anthurium

[Ray]

Those high-TDS pour-through numbers show that you’re leaching something out of the media, suggesting the possibility of “poisoning”. What that may be, I can only guess, but fertilizer buildup in the media would be my first guess, and salt (yes, NaCl) out of the coir ingredients would be second. Zeolites, like charcoal, are great absorbers, but once saturated, become little toxic pockets.

Have you tried doing the pour-through tests on fresh media, after watering it with just RO?

Personally, I’d repot everything into fresh potting soil (not that mishmash), replace your current, complex, yet still incomplete feeding regimen with a simpler one, using ONLY a complete fertilizer formula (Akerne’s Rain Mix is a good one in EU), and reducing the concentration and frequency of feeding.

The point of my prior post was to point out that plants don’t add mass quickly, don’t need a lot of fertilizer to do so, but DO need a great deal of water.

[Ale_V]

Thank you so much, Ray, for your feedback!

Rainmix is exactly what I use for my orchids—luckily, I already have it! What concentration do you recommend? Should I still add CalMag to the mix?

Repotting everything is unfortunately not possible right now (I’m leaving in three days for a month-long work trip). Is there a way to neutralize, even partially, any potential NaCl if that’s the cause?

Later, I’ll try testing each material individually. To do this, can I soak a sample of the material in 500 ml of water for 30 minutes, remove the material, and then test the remaining water?

Thanks so much!

[Ray]

Originally Posted by Ale_V

Thank you so much, Ray, for your feedback!

Rainmix is exactly what I use for my orchids—luckily, I already have it! What concentration do you recommend?

Maybe about a 150 ppm N solution once a week.

Should I still add CalMag to the mix?

Absolutely not. It already has plenty in the formula. Adding more is not an improvement. In fact it might interfere with the uptake of other nutrient ions.

Repotting everything is unfortunately not possible right now (I’m leaving in three days for a month-long work trip). Is there a way to neutralize, even partially, any potential NaCl if that’s the cause?

Nope, not really. Maybe flood the hell out of the pots with RO several times.

Later, I’ll try testing each material individually. To do this, can I soak a sample of the material in 500 ml of water for 30 minutes, remove the material, and then test the remaining water?

Thanks so much!

That would be fine. What you’re trying to do is learn where the excess is coming from, so even putting the medium in a funnel using a paper towel as the barrier and pouring the RO through it one time might be sufficient. You’re looking for an indication, not a measurement.