Overwatering and stem rot
Wet soil with soft, yellowing lower leaves is the number-one way to lose a rex begonia.
Diagnosis
Overwatering and stem rot
What's happening
Rex begonias grow from a fleshy rhizome and a shallow, fine root system that needs air as much as water. When the mix stays soggy, those roots and the rhizome can't breathe, so they begin to rot. The plant collapses its oldest leaves first, which go soft, translucent, and yellow before the stems turn to mush at the base.
How to fix it
Stop watering immediately and let the mix dry out. Slip the plant out of its pot and inspect the rhizome and roots — firm, pale tissue is healthy, while brown or mushy parts are rotting. Cut away every soft section with sterilized snips and repot the firm remainder into fresh, airy, well-draining mix in a pot with drainage holes. From now on, water only when the top inch feels dry, and pour at the soil line rather than over the leaves and rhizome.
What fixes it
- A soil moisture meter — A moisture meter removes the guesswork — only water when it reads dry an inch down, which keeps the rhizome safe.
If that doesn't fix it
This is general guidance based on common symptoms; individual plants vary.
Read the full Rex Begonia care guide →
Reviewed June 2026 · how we check this