From my roots' perspective, this is the most common assault. My Mediterranean heritage means I am built for well-drained, gritty soil and infrequent, deep drinks. When water is applied too often, it fills the air pockets in the soil around my roots. Without oxygen, my root system begins to suffocate and rot. This rot prevents me from drawing up any water or nutrients into my stems and leaves, no matter how saturated the soil is. The result is a cruel paradox: I am dying of thirst while standing in water. The browning you see is the tissue of my leaves and stems necrotizing and dying from the tips inward, a direct signal of my root system's failure.
While I am drought-tolerant, I am not a cactus. There is a limit to my resilience. If the soil becomes completely desiccated for too long, my cellular structures begin to break down. The leaves, which are small and designed to conserve moisture, will sacrifice themselves to protect the main stem. They lose their turgor pressure, becoming brittle, and then turn brown and crispy, typically starting at the outer edges before the entire plant succumbs. This is a last-ditch effort to conserve the little moisture I have left for my core, hoping for a eventual reprieve in the form of a deep watering.
My number one requirement is soil that lets my roots breathe. Heavy, clay-based, or compacted soils are a death sentence for me. They act like a sponge, holding water for far too long and creating the same anoxic (oxygen-deprived) conditions as overwatering. Even if you water correctly, the wrong soil will lead to the same brown, rotting demise. I need a loose, sharply draining mix, often amended with sand, perlite, or fine gravel. If my container lacks adequate drainage holes, the problem is compounded, creating a stagnant pool at the bottom of my pot that my roots cannot escape.
Environmental stress, particularly from wet conditions, often invites secondary invaders. Fungal pathogens like root rot (Phytophthora) or Botrytis (grey mold) thrive in the very conditions that weaken me. These organisms actively attack my tissues, causing browning, blackening, and decay. Similarly, while I am fairly pest-resistant due to my aromatic oils, severe infestations from spider mites or aphids can cause stress and physical damage. These pests pierce my leaves and stems to suck out my sap, leaving behind damaged cells that desiccate and turn brown.
It is also possible that what you are witnessing is a part of my natural, albeit less attractive, life cycle. As I grow, particularly in the center of a mature plant, older woody stems may become shaded. Without sufficient light, these inner sections will naturally brown and become woody as I direct my energy to new, outer growth. This is a form of self-pruning. While this is normal, it can be exacerbated if I am not pruned or harvested regularly, which encourages fresh, green growth and improves air circulation through my branches.
