The answer to 'sod overgrown' is that sod can become overgrown and thick over time, which can lead to issues like poor drainage, difficulty mowing, and an unhealthy lawn. Common causes include lack of regular mowing, excessive thatch buildup, and soil compaction. Symptoms include a dense, matted appearance, difficulty penetrating the soil, and reduced grass growth.
The best solution is to dethatch or aerate the lawn to break up the thick thatch layer and improve soil oxygen and water penetration. This can be done with a power rake, core aerator, or dethatching machine. Overseeding with new grass seed can also help fill in bare or thin areas. If the issue is severe, you may need to completely remove and replace the sod. For extensive work or if you're unsure, it's best to call a professional landscaper who can assess the situation and provide the appropriate treatment.