Dormancy, not death

What's happening

Oxalis triangularis naturally takes rest periods, especially after a long bloom, in summer heat, or in low light. The leaves yellow, flop, and die back while the bulbs underground stay alive and simply pause. People often mistake this for a dead plant and toss a perfectly healthy one.

How to fix it

Before assuming the worst, check the soil and bulbs — if the bulbs are still firm, it's dormant. Cut away all the spent foliage, move the pot somewhere cool and shaded, and water only lightly every couple of weeks to keep the bulbs from shriveling. After three to four weeks of rest, return it to bright indirect light, resume normal watering, and fresh stems will sprout from the bulbs.

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