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? My room has a two large east facing and two large south facing windows, so it’s bright all day almost every day. I have the calathea a few feet away from one of the windows, so it still gets bright light, but still on the darker side (I’ve read that calatheas prefer lower light(?)). I recently moved it from my desk to a slightly brighter spot. I have 3 humidifiers that I run whenever the humidity gets a bit low, so I’m fairly certain that isn’t the problem. I water whenever the top inch or two of soil gets dry (I’ve read that calatheas prefer moist soil that isn’t wet(?)). I repotted the rattlesnake a month or two ago, so I’m pretty sure it doesn’t have root rot. I’m very careful about pests, so I don’t think that’s the problem either. I have a calathea orbifolia that’s doing good right next to where the rattlesnake used to be, so I’m confused as to why the rattlesnake isn’t doing well.

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.
This 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