How to Stop Grass Buildup Under Any Lawn Mower Deck. Grass buildup under a lawn mower deck is a pain. It leaves clumps of grass on the lawn, rusts out the deck, and leads to messy, slow cutting due to reduced air flow. A protective coating.
If you haven't cut back you Ornamental Grasses now is the time, as well as dividing. Cut the grasses back to about from the ground. I use a nice sharp Garden Spade to divide and separate. Dividing should be done every two to three years.