From my perspective, the most common reason my leaf edges turn brown is directly related to what you pour into my pot. I am very sensitive to the minerals and chemicals found in tap water, especially chlorine and fluoride. When you water me with this, the minerals build up in my soil over time. My roots, in their effort to take in moisture, also absorb these excess salts. They travel to the tips and edges of my leaves, where they accumulate and essentially burn the tissue, causing those unsightly brown, crispy spots. This is my way of showing you that the water is toxic to my system.
Your watering habits are a constant conversation with my root system. If you give me too much water too often, my delicate, hair-like roots will begin to rot in the soggy soil. Once they rot, they can no longer absorb water and nutrients. The first sign of this distress is often wilting or soft, brown spots on my leaves, as the parts farthest from the compromised roots are starved of moisture. Conversely, if you let my soil become completely dry and brittle, my roots will desiccate and die. Without a healthy root system to supply water, the edges of my leaves will dry out and turn brown as a clear signal of my thirst.
I hail from the tropical, high-humidity understory forests of East Africa. The air in your home, especially during winter when heaters are running, is often extremely dry to me. When the humidity drops too low, the moisture in my leaves evaporates faster than my roots can replace it. This loss of water is most acute at the leaf margins, causing them to dry out, become brittle, and turn brown. It is a slow, persistent stress that weakens me over time. I am not a cactus; I thrive in moist, balmy air.
While I need nutrients to produce my beautiful blooms, too much fertilizer is harmful. Applying fertilizer too frequently or at too high a concentration leads to a buildup of soluble salts in the soil. This creates a situation similar to using tap water, but often more severe. The high salt concentration in the soil can actually pull water out of my roots through osmosis, a process called fertilizer burn. This root damage prevents water uptake, and the excess salts are drawn to the leaf edges, resulting in brown, scorched-looking margins. It is a case of too much of a good thing being very damaging.
Finally, please check where my leaves are resting. If my lower leaves are constantly pressed against the cold, damp rim of a ceramic pot, or if they are touching a windowsill that becomes cold at night, this contact can cause localized damage. The persistent moisture can promote rot, and the cold surface can damage the leaf cells, both leading to brown spots. Similarly, if a leaf is consistently touching a window on a sunny day, the concentrated heat can scorch it. I prefer my foliage to be free and unencumbered.
