Winter grass seeds germinate when temperatures are cool in fall, often out competing other, more well-behaved grasses. ... It usually dies out in the heat of summer, but by that time, turfgrass is weakened and is easily infected with yet more winter grass when weather again turns cool.

What happens to winter grass in summer?

Wintergrass is a prolific seeder that will eventually overtake the lawn in winter. It seeds in Autumn, Winter and Spring and dies off throughout prolonged hot periods in the Summer. This leaves a weakened lawn that will become infected with even more Wintergrass the following cool season.

Can I kill winter grass in summer?

With this in mind, Winter Grass is best and most easily killed in May, pre-emergent, and before we can even see the weed. You may still kill Winter Grass into June and sometimes July.