I have a few spots in the yard where theres dead grass. Ive found these plugs are much easier to take care of instead of watering seed in the yard. the square pots on the right are fine fescue for shady areas. Any idea what would kill the grass in the one pot? The only difference is the dead one was older than the other two. I think it was planted about a month sooner. The same tome the pots on the left were planted.