What’s wrong with miltoniopsis leaves
 

Hi.
Something is happening with my miltoniopsis. The leaf tips are turning brown and then it spreads it makes the entire leaf yellow. Is it the fertilizer ?
I keep it Away from windows. Day temperatures are in the 80-90F. I turn on the AC for the night and keep the room at 72F. Humidity is around 50-60%. I water it as needed, about every 2-3 days. Roots look nice and green. It’s growing in ceramis with sphagnum moss on top. I was fertilizing it every weakly weekly (I used 20-10-20). But since I noticed those brown tips I stopped fertilizing. So now just watering it with sink water.
Any thoughts what’s causing the problem? Thanks

Generally speaking Miltoniopsis prefer cooler conditions. I would do the reverse of what you are doing - aircon during the day and open windows at night, where temps can drop to the 60s and airflow is better. Yep, I know. Easier said than done. Photo is mine in the basement. Temperature hit 77f 1x, the rest - under 72f.

At night Temps are not Going down to 60’s. It’s in the 70-80F. So you think it’s the heat that does that to the leaves not the fertilizer?

Persistent heat causes issues.
As we head into fall overnight temps do drop.... ours here already have.

Here in NYC temps are at its highest. So poor miltoniopsis is suffering. Should I cut those yellowing leaves off? Keep AC running through the day, right? That’s one expensive plant lol.
Thank you guys😊