Quick answer: Dry spots can result from poor sprinkler overlap, clogged or incorrect nozzles, tilted or sunken heads, blocked spray, low pressure, landscape changes, or a watering schedule that does not match the zone. Adding more runtime is not always the right fix.
Coverage problems are common
Sprinklers are typically designed to overlap coverage. A head that is tilted, buried or fitted with the wrong nozzle can leave a gap even though the zone appears to run normally.
Check for physical obstruction
Growing shrubs, ornamental grasses, new fencing and landscape changes can block spray patterns that once worked correctly.
Pressure and flow matter
If several heads have shortened throw distance, investigate low pressure on the zone before increasing runtime.
Fix distribution before adding water
Longer watering may overwater healthy areas while the poorly covered spot remains dry. Correcting the distribution problem is usually more efficient.
