Crab Grass first appears on Hole 325.
Play the Crabgrass Card before the count reaches 0 and spreads (5).
Crabgrass cards have a counter that counts down every time you play a card that is not the Crab Grass card.
If the card's timer reaches 0, the Crabgrass card will change into a Rough Hazard and change cards around it into Rough Hazards as well. It might even change another card into a Crabgrass card.
Clearing a Crabgrass card works just like clearing a Rough card.