Symptoms of Overwatering Hydrangeas

Wilting

• Wilting on hot summer days or in late afternoons is normal for hydrangea, however, sudden wilting of the foliage on one or more shoots is the first symptom of this disease. Normally as water moves into a plant cell, the cell itself expands but the strong cell wall does not expand as rapidly which causes pressure to build inside the cell. This pressure causes rigidity that supports the plant in areas such as leaves. As the roots of hydrangea begin to rot, less and less water is able to reach the leaves. The lessening of fluid means the plant cell cannot exert mechanical pressure against the cell wall which causes the leaves to "deflate."

Yellowing

• Many things, including over watering, can cause yellowing of foliage. Since nitrogen deficiency causes yellowing of old leaves and iron deficiency causes yellowing of new leaves, the hydrangea roots' inability to absorb these nutrients or carry them to the leaves causes the foliage to turn yellow.

Leaf Drop

• Although leaf drop in the fall is a natural process for hydrangea, leaf drop after wilting or yellowing at any other time is a cause for concern. As with both yellowing and wilting, leaf drop occurs because the plant's main stem is not getting enough water and nutrients to the leaf. After the wilting or yellowing, the amount of water and nutrients continue to diminish until nothing is able to reach the leaf stem at which point both the leaf and leaf stem dry up, die and fall from the hydrangea.

Stunted Leaves

• Stunted leaves are a sign of root rot slowly invading the root system and restricting the water and nutrient flow to the leaves. The rate that the leaves grow slows and the mature leaves do not reach normal size.

Spotting or Discoloration of Leaves

• When hydrangea is overwatered, leaves become spotted or discolored. The Phytophthora nicotiana fungus invades the crown of the hydrangea, the plant tissue under the bark becomes brown and continues up the stem beyond the soil line. When the fungus gets to the leaves, the leaves get spots, become discolored and the edges become brown and brittle.

Brown and Brittle Feeder Roots

• Normally hydrangea feeder roots are off-white and slightly flexible. When the hydrangea is overwatered the feeder roots become brown and brittle. This condition may appear in part or all of the root system.