A number of problems on landscape plants can be influenced by soil moisture, either how much water is applied or how it is applied.
Overhead sprinkling is a common practice in most landscapes, but water that sits on the leaves during the night can lead to increased disease problems in susceptible plants. Applying water overhead shortly after applying pesticides may wash off much of the spray.
Shrubs in the foundation planting may suffer from serious water-related problems. Plants placed directly in front of a downspout can develop root problems during rainy weather due to the large amount of water put in their root zone from the down spout. The other extreme also occurs in foundation plantings. If plants are placed under large a overhang, the overhang prevents rainfall from reaching them and they suffer from too little water.
Homeowners with swimming pools will sometimes water their landscape plant with the water used to backwash the filter. The water is no problem, but the chemicals in the water can injure plants.
Keeping the lawn growing can involve frequent watering, especially if underground sprinklers attached to a time clock are used. It is impossible to water the lawn without also watering the other plants in the landscape. When the lawn is being watered frequently, check the root zones of trees and shrubs to make sure they are not getting too much water. Plants growing in areas that may be slightly lower than the rest of the lawn are most likely to be overwatered.