What is the earliest indication that something is wrong with a plant?

A reduced growth rate serves as an early indication that something may be wrong with a plant because it reflects a fundamental problem affecting the plant's overall health. This could stem from various underlying issues, such as nutrient deficiencies, improper watering, or disease. When a plant is stressed or unhealthy, its ability to grow and develop is hindered, making a reduction in growth rate one of the first noticeable signs for a grower.

Yellowish leaves, brown leaf margins, and brown roots can also signal problems, but they often indicate more advanced stages of stress or specific issues that may have developed over time. For instance, yellowing leaves often suggest nutrient deficiencies or overwatering, while brown leaf edges might indicate problems with water uptake or environmental stress. Brown roots typically point to root rot or other serious conditions. Thus, while those symptoms are important, they often follow an initial decreased growth rate, emphasizing the significance of growth rate as a key early warning sign.