Q.I Have A Rattlesnake Calathea That I’ve Been Caring For For A Few Months. It’s Been Doing Fine Up Until A Few Weeks Ago, When It
started to get crispy brown leaves. I don’t think it has root rot, and I keep the humidity on the higher end. Can anyone tell me what I’m doing wrong? If this is the wrong place to ask a houseplant question, please let me know. My room has two large east facing and two large south facing windows, so it’s bright for the whole day. I keep the calathea on a shelf on my desk, where it gets bright, indirect light almost every day. I water it when the top inch or so of the soil gets dry. I have 3 humidifiers that I run whenever the humidity gets low. I’ve cared for calatheas in the past and currently have an Orbifolia that’s doing well in a similar spot. If it makes any difference, the rattlesnake is on the same shelf as a hoya and a spider plant. I recently moved it from a slightly darker spot next to a philodendron hastatum (Silver sword). Any response is appreciated.

Certified GKH Gardening Expert
I see a key piece of information... Repotting... Once you repot your plant, that soil will not be colonized by roots. This will mean that it takes longer to dry out, and will cause disease faster. Until the roots colonize that portion of the soil, I would water less than usual. You might even wait until the leaves droop, slightly, to water. Unfortunately, your photos did not come through, so I am unable to see the damage in question. I do suspect damage from overly wet soils, deeper in the container. Be sure to use a fungicide, just in case, as it can help prevent issues, as well.
his collection of articles will help: https://www.gardeningknowhow.com/houseplants/calathea-plants
This will help you with fungicide use:
https://www.gardeningknowhow.com/garden-how-to/info/using-fungicides-in-garden.htm