From my perspective, water is life, but it is also a source of great stress. My roots need a consistent and balanced environment. When you provide too little water, I cannot transport essential nutrients to my leaves, especially the delicate tips which are the furthest points from my root system. They dry out and die first, turning brown and crispy. Conversely, when you provide too much water, you suffocate me. My roots need oxygen to function, and waterlogged soil drowns them, causing them to rot. Once my root system is compromised, I can no longer absorb water effectively, leading to a paradoxical state of drought even though the soil is wet. This also results in brown, often soft and mushy, leaf tips as the tissues break down.
As a begonia, I hail from tropical and subtropical regions where the air is thick with moisture. The air in most homes is far too dry for my liking. Low humidity causes a rapid rate of transpiration, where I lose more water from my leaves than my roots can absorb. The leaf tips, being the most vulnerable, are the first to desiccate and turn brown. Similarly, I am sensitive to extreme temperatures. Placing me near a hot radiator, a cold drafty window, or an air conditioning vent subjects me to sudden shifts. This thermal stress damages my cells, and the leaf tips often show this damage first by browning as a clear sign of my discomfort.
You may be trying to help me grow with fertilizer, but too much of a good thing is toxic. An overabundance of mineral salts from fertilizer builds up in my soil. This creates a hostile environment for my roots, making it difficult for me to take up water and essentially causing a chemical burn. The excess salts are sometimes pushed to the tips of my leaves, where they accumulate and burn the tissue, resulting in brown, crispy margins. Furthermore, the chemicals often found in tap water, such as chlorine, fluoride, and dissolved solids, can be harsh on my system. Over time, these chemicals also build up in the soil and in my leaves, leading to tip burn.
While I try to be resilient, I can fall victim to pests and diseases. Sap-sucking insects like spider mites, thrips, or aphids pierce my leaf tissues and feed on my vital fluids. Their feeding activity damages the cells, often causing stippling, yellowing, and browning that can start at the tips. Fungal and bacterial diseases, often encouraged by overly wet conditions on my foliage or in my soil, can also manifest as brown spots or patches. If these begin at the leaf tips, it is a sign the infection is spreading through the leaf's vascular system or that the weakened tip was the first point of entry.
