Why are my plant leaves turning brown or showing brown flecks?

If you’ve noticed leaf bronzing or tiny brown flecks on your plants’ leaves, it is possible that there is too much iron in your garden’s soil. Too much iron in your garden’s soil needs to be fixed by lowering the iron content available to plants. This can be done by adjusting the soil pH, balancing iron with other micronutrients, or by improving aeration and drainage of water.

Iron is used as a catalyst to synthesize chlorophyll, which is required for photosynthesis.

Without chlorophyll, plants would not be able to produce enough energy to grow. Iron is also used for a plant’s protein synthesis and for nitrogen fixation and reduction.

Having too much iron in your soil is called “iron excess” or “iron toxicity”. While small amounts of micronutrients like iron are needed for plant growth, having too much of them can be harmful to the plant. A careful balance is needed.

The plants in your garden may be suffering from iron toxicity if leaves show signs of bronzing (that is, getting darker), if brown spots form on the leaves, or if the plant’s growth becomes stunted.

Bronzing is the most common symptom. While small amounts of iron are needed for chlorophyll production, having too much iron affects the chlorophyll itself, making it darker. This prevents the plant from absorbing sunlight.

Having too much iron also interrupts vital cell processes that produce proteins and energy for the plant. If left untreated, the plant will eventually die.