From my perspective, the most critical drama unfolds unseen, beneath the soil. When you overwater me, my roots are plunged into a perpetual, airless swamp. I cannot breathe. The oxygen I need for my root cells to function is pushed out by water, and they begin to suffocate and break down. This creates a prime environment for rot-causing fungi and bacteria to attack. My roots turn from a healthy white or tan to a mushy, dark brown or black, and they may even smell foul. Conversely, when I am underwatered, my roots are simply desperate for moisture. They become dry, brittle, and may start to shrivel. They are not rotten, but they are desiccated and unable to perform their sole duty: to absorb water and nutrients to send up to my stems and leaves.
My leaves are my most vocal communicators, and they tell very different stories based on your watering habits. If you have given me too much water, my leaves will feel soft, mushy, and limp. They may become translucent or see-through in patches. This is because the cells in my leaves are so waterlogged that they have burst, a condition you call oedema. You might even see blisters or bumps on the underside of my leaves before they turn yellow and drop off. In stark contrast, an underwatered Begonia has leaves that feel crispy, dry, and papery. They lose their turgor pressure—the water pressure that keeps my cells rigid—and will droop pathetically. They will often develop dry, brown, crispy edges and may curl inward in a desperate attempt to reduce surface area and conserve moisture before they eventually fall.
While both conditions can lead to yellowing leaves, the context and pattern are crucial for diagnosis. Overwatering-induced yellowing is often a widespread, generalized chlorosis. You will see large areas of my leaves, or even entire leaves, turning a pale, sickly yellow. This happens because the rotten roots can no longer uptake essential nutrients, starving me. The yellowing is soft and often accompanied by that tell-tale wilting mushiness. Underwatering, however, typically presents with browning first. The yellowing is often more localized to the edges of the leaves or the tips, which then rapidly desiccate into a dry, crispy brown. The green parts of the leaf may also appear dull or faded, but they will retain a dry texture, not a wet one.
Finally, pay attention to my stem and the environment I am planted in. An overwatered Begonia will often have a soft, mushy stem near the soil line. You might gently press it and find it feels unstable and rotten, a clear sign of advanced root rot. The soil will also feel cold, soggy, and clumpy days after you watered. An underwatered Begonia’s stem will be dry, brittle, and may even become woody or shriveled. It holds its structure but lacks vitality. The soil will be extremely dry, pulling away from the edges of the pot, and will feel dusty to the touch. Lifting the pot will also feel surprisingly light, as there is no water adding weight.
