Why does your Begonia tuberhybrida have yellow leaves? Diagnose the cause and fix it with our step-by-step guide.
Tuberous Begonias are highly susceptible to fungal pathogens like Phytophthora when the tuber remains in saturated soil. Excessive moisture causes oxygen deprivation, leading to chlorosis (yellowing) before the foliage eventually collapses.
A lack of nitrogen prevents the plant from producing sufficient chlorophyll, causing older leaves to turn yellow first. This is common in Begonias if they have been planted in depleted potting mix for a full growing season.
Tuberous Begonias are tender perennials that thrive in moderate temperatures; sudden drops in temperature can trigger a physiological response resulting in yellowing leaves. Cold soil specifically can inhibit nutrient uptake and damage the tuber's metabolic processes.
As day length decreases and temperatures cool, Tuberous Begonias naturally begin to shut down for dormancy. Yellowing of the foliage is a standard part of the plant withdrawing energy back into the tuber.
Your plant might also be experiencing one of these issues:
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