Natural leaf aging

What's happening

A moth orchid holds only a handful of leaves at a time and retires its oldest one every so often to put energy into new leaves and flower spikes. If just the lowest, oldest leaf is yellowing while the roots are firm and green and the rest of the plant looks healthy, nothing is wrong.

How to fix it

Let the spent leaf yellow and detach on its own, or once it's mostly yellow ease it off gently where it meets the stem. Carry on with your normal care and watch that the yellowing stays limited to that single oldest leaf and doesn't climb upward, which would signal a watering or crown problem instead.

This is general guidance based on common symptoms; individual plants vary.