Good aerated soil will allow room for water,nutrients,air and room for roots to move.
Thatch can prevent water and nutrients from reaching the root zone. If your thatch is more than half an inch thick your grass will struggle to grow.
Thatching should be done in April or May to allow your lawn time to recover.
Maintaining a proper mowing routine is key. Grass is ready to be mowed when it reaches 3 inches high.