What negative effect can overwatering have on plant health?

Overwatering can lead to root rot and suffocation mainly because excess water fills the air spaces in the soil, which deprives the roots of the oxygen they need for healthy growth and function. Roots are critical for a plant's intake of water and nutrients, and when they are submerged in water for prolonged periods, they can begin to decay. This decay leads to root rot, which can cause severe damage to the plant.

Additionally, the lack of oxygen in overly saturated soil can create anaerobic conditions, making it difficult for beneficial microorganisms to thrive. Healthy soil relies on a balance of moisture, air, and nutrients, and overwatering disrupts this balance, leading to a range of problems that ultimately affect plant health and vigor.