According to the UC Integrated Pest Management webpage on Water deficit and excess, "Inappropriate irrigation is probably the most common cause of landscape plant damage. Too little or too much soil moisture can adversely affect most any aspect of the appearance, development, and growth of any plant."

UC also provides information about Estimating irrigation needs, read their webpage for tips on observing plants and monitoring soil moisture. We have our own Checking Soil Moisture tip that tells you how to check how deep your irrigation has penetrated.