A newly laid sod lawn requires special care to ensure proper root establishment and healthy grass. Dead sod is a sign that one or more of the basic maintenance needs is not met, and this should be corrected immediately to prevent further decline. If the sod is completely dead -- brown, dry and brittle -- revival is not likely, but you can take immediate action at the first sign of dying sod to revive it to a healthy state.
Before taking action to revive dead sod, inspect it carefully to determine the cause of the problem. First, rule out the possibility that the grass is just dormant and not actually dead. Grass goes dormant in late fall through winter; normal growth and appearance should resume in early spring after the last frost. Compare the conditions of the dead or dying sod with the conditions in healthy sod areas to help narrow down the cause. If the dead sod and soil beneath are either soaking wet or extremely dry, improper watering is likely the cause. If you recently fertilized the dead area, overfertilization may be the problem. Mowing the grass too short or too soon after laying sod can also restrict the potential for photosynthesis. Pull back a strip of sod to check for root attachment between the sod soil and the soil layer beneath the strips. Causes of failure to establish roots include insufficient contact between the sod and soil layer -- usually from improper grading -- and compacted soil beneath the sod layer, usually caused heavy foot traffic.
New sod requires daily application of about 1/2 inch of water, to soak through the sod and top few inches of soil. After about a week, gradually reduce the frequency of watering while increasing the amount applied at once. Longer watering periods soak moisture deeper into the soil, which helps the roots work their way into the soil layer. Adjust your watering accordingly to address problems with insufficient or excess watering. Pull back a corner of the sod to check the level of moisture in the sod layer and soil. Soaked sod is acceptable for the first week, because sod dries out so quickly, but the soil should be only moist in the following weeks. While grass needs water to thrive, overwatering fills in all the oxygen space in the soil, cutting off the oxygen supply to the roots.
Frequent mowing boosts grass growth -- just as haircuts help promote healthy hair -- but scalping the sod can kill it. Adjustments to mowing height and frequency, coupled with ample water, should help restore the sod's health. New sod should never be mowed until it reaches at least 3 inches, but you might let it reach 4 to 5 inches in height if you notice problems with the grass. Two inches is sometimes suggested as the final cutting height, but this might not leave enough grass blade surface to collect sun rays. Instead, adjust the mower deck height to 3 to 3 1/2 inches. It might be necessary to dethatch the lawn with a dethatching rake to remove the dead grass so the roots breathe better. If necessary, overseed the bare spots with grass seed in fall or spring, or replace the patches with new sod.
Sod roots cannot expand into the soil below if there are large gaps between the sod and soil layers. Roll up the dying sod and regrade the soil so it's completely smooth. Flatten out any bumps and fill in grooves in the original grade. Water the soil until it's evenly moist before relaying the sod. Foot traffic on new sod packs down the soil layer before the roots can penetrate and establish in the soil. For best results, keep all foot traffic off the sod for the first week, and limit use to only light foot traffic for the first month after you lay the sod. If you notice soil compaction upon inspection of the soil, roll back the sod and use a shovel or similar tool to loosen the top 4 to 6 inches of soil.
Fertilizer provides the necessary nutrients to boost grass growth -- like a vitamin supplements nutrition -- but too much fertilizer can burn the grass and roots. Have the soil tested to determine the correct amount of fertilizer for the lawn, usually no more than 3/4 pound of nitrogen per 1,000 square feet. Fertilizer should be applied to the soil before laying sod, so wait at least one month before applying more fertilizer. The best option to fix overfertilization is to simply wait out the damage. While extra water dilutes the fertilizer, overwatering can cause problems with rot. Assess the damage one to two months after fertilizer application -- the sod might revive with proper watering after the excess fertilizer works its way out of the soil.
Even with special care to fix the problem, it may not be possible to revive dead sod. In some cases, the lawn might have several dead patches you need to replace. Cut out a dead patch of sod with a sod knife or other sharp, clean garden-use knife. Loosen the soil beneath the old sod, and water until moist. Cut a piece of new sod to fit the space and set it in place. Roll over the patch lightly to ensure good contact with between the roots and soil. Care for the replacement patches just as you would when caring for a new sod lawn.