Description
Overwatering is one of the most common plant problems, especially in areas where the soil is heavy and poorly drained. Plant roots require oxygen to function normally. They obtain oxygen from tiny air spaces (pores) in the soil. When the soil is irrigated, air is pushed out of the soil pores and replaced with water. Pores refill with air when water drains through the soil, when plant roots absorb water, and when water evaporates up through the soil surface. If water is constantly reapplied, the soil pores will remain filled with water. Roots growing in such soil die because they cannot absorb the oxygen they need. The dying roots decay and are unable to supply the plant with water and nutrients. This results in plant stunting, weakening, and eventually death. Sometimes plants respond to wet soil conditions by growing roots just under (in some cases just above) the soil surface where the soil dries out more rapidly and oxygen is more available. These plants are often stunted and slow growing. They may wilt and die quickly if the soil is allowed to dry out past their shallow root zone. Overwatering frequently causes root rot diseases. (For more information about root rot, see Water Molds.)
Control
Allow the soil to dry out somewhat between waterings. (For information on watering, see About Watering.) If your soil is heavy and poorly drained, improve the soil drainage. (For more information on improving drainage, see Soil Structure, Groundwater.) Some plants can tolerate wet soil (for a list, see Plants for Wet Soil).
