Signs of Over Watering New Sod
New sod does need to be watered more often than established grass to ensure that it will take root, but it is possible to put too much water on the sod. Too much water on your sod could make it soggy, which prevents it from establishing a strong root system. The sod is more susceptible to insect, fungus and disease damage if it gets too much water. Once you spot the signs of excessive watering, skip one or two watering sessions so the sod and soil underneath are only moist. not soggy.
Failure to Knit into the Soil
The grass roots on the sod should begin to knit with the underlying soil after one to three weeks. Test the sod each week, starting on the seventh day after it was laid. Gently lift a corner of the sod. If it is difficult to move, the roots are beginning to grow into the soil, but if you can still pick it up with gentle force three weeks after laying it, you may be over watering.
Over watering can cause the roots of the sod to rot. During the first week after laying new sod, look under the sod at the roots. If they show signs of rotting, you may be using too much water or watering too frequently. New sod requires daily watering, and sometimes, you may need to water more than once a day to prevent the soil from drying.
Soggy Soil or Sod
Lift up the sod before the roots have begun to grow into the soil after watering it. Touch the soil and sod with your finger. Both should feel damp, but neither should be muddy. Sod should not feel like a sponge full of water. If it does, you are over watering. Too much water will prevent the roots from growing into the soil beneath.
The depth of moisture in the soil below the sod indicates if you are over watering. Immediately after installing the sod, and until it takes root, water the sod to moisten the top 1 inch of the soil underneath. Once the sod has begun to establish itself in the soil, reduce the number of times you water, but with each watering session, you need to make the soil damp down to 6 inches below the surface. Insert a long screwdriver into the soil. It should feel moist along the first 6 inches if you are watering correctly. Over watering will make the soil damp lower than 6 inches.
University of Rhode Island Landscape Horticulture Program: Installing a Sod Lawn
University of California Integrated Pest Management Program: Irrigating a New Lawn
Purdue University Cooperative Extension: Irrigation Practices for Homelawns