Overwatering

What's happening

Hoya kerrii is a semi-succulent that stores water in its thick heart-shaped leaves, so it needs the soil to dry out fully between drinks. When roots sit in soggy mix they can't get oxygen and begin to rot, and the plant sheds its oldest leaves first — they turn a translucent yellow and go soft or mushy rather than crisp.

How to fix it

Stop watering immediately and let the soil dry out completely. Slip the plant out of its pot and check the roots — firm, pale roots are healthy, so trim any brown, mushy ones with sterilized scissors and repot into a fast-draining, chunky mix in a pot with drainage holes. Going forward, water only when the soil is bone dry an inch or two down, and far less often in winter. A single-leaf Hoya kerrii with no vine especially rots fast, so err on the dry side.

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