Indiana Accredited Horticulture Initial Practice Exam

Yellowing leaves and wilting are a primary indication of overwatering in houseplants. When plants receive too much water, their roots can become waterlogged, leading to a lack of oxygen in the root zone. This condition can cause the roots to become damaged or to rot, which negatively impacts the plant's ability to uptake nutrients and water. As a result, leaves may start to yellow and the plant may exhibit wilting, even when the soil is moist.

In contrast, dark green leaves can be a sign of healthy, well-watered plants or excessive nitrogen. Rapid growth of flowers typically indicates healthy growth conditions, not overwatering. Thickened stems may occur due to other factors like adequate watering and nutrient availability or might indicate a plant adapting to stress rather than showing signs of overwatering. Hence, yellowing leaves and wilting is the most straightforward and common symptom directly tied to overwatering.