Weakened or dying geraniums are often the result of issues such as improper care and fungal diseases. While geraniums are considered relatively hardy plants, they still require proper care to fully thrive.
Over watering is a common problem with geraniums. Typically, symptoms of over watering include unopened buds that fall off the plant or dry buds. Over watering can also cause root rot, a condition that generally causes plants to wilt and turn yellow until they eventually die. However, if root rot is caught early, many plants can be saved.
Frost can also damage or kill geraniums. When geraniums are exposed to frost, cold penetrates the stems and kills the plant tissue.