Hibiscus Oedema: Granular Deposits from Humidity Fluctuations

A miniature hibiscus in a sunroom developed irregular, sand-like granular deposits on leaves and stems. UGA tropical plant expert Bodie Pennisi identified this as oedema, a physiological disorder common in greenhouse plants like geraniums, sweet potato vine, and poinsettias. High humidity and fluctuating moisture cause cells to rupture, forming the deposits.

Check soil moisture before watering; only water when the soil feels dry. The deposits can be brushed off harmlessly.