From my perspective as a rosemary plant, my roots are my lungs and my mouth. I need to breathe in the soil, taking in oxygen to power my cellular processes. When you water me too frequently or plant me in a dense, poorly draining soil mix, you are essentially drowning me. The air pockets in the soil fill with water, creating an anaerobic environment. My roots begin to rot, turning brown and mushy. Once this root system is compromised, I can no longer absorb water or nutrients, no matter how much is in the soil. This is a cruel irony—my leaves droop and wilt from thirst while my roots are sitting in water. This is the most common reason for my decline.
While I despise wet feet, I am not a cactus. My native Mediterranean environment provides infrequent but deep watering. If you forget about me for too long, allowing my soil to become completely dry and dusty for an extended period, I will enter a state of severe drought stress. The water pressure (turgor pressure) inside my cells is what keeps my sturdy, needle-like leaves erect and firm. Without a consistent water supply, that pressure drops, and my cells collapse like deflated balloons. This causes my leaves to first become limp and droopy, and if the situation is not corrected, they will turn brown, crisp, and die.
You may not see it, but beneath the soil, a silent crisis may be unfolding. If I have been growing in the same container for many seasons, my root system may have completely filled the pot. There is simply no more room for me to grow. This dense mat of roots absorbs water incredibly quickly and leaves little room for soil, which holds the moisture and nutrients I need. Even with regular watering, the water might just run down the inside of the pot without ever being absorbed by the root ball. I am effectively being strangled by my own success, leading to a constant state of wilt and stunted growth.
Sometimes, the trouble is not your fault but is due to an invisible attacker. Microscopic pests called root-knot nematodes can invade my root system. These worms feed on my root tissues, causing the formation of grotesque galls or knots that block my vascular system. Think of it as a blood clot; water and nutrients cannot pass through these blockages. This prevents life-sustaining resources from reaching my stems and leaves, causing them to wilt and yellow, despite otherwise perfect growing conditions. This is a serious and often overlooked cause of my distress.
