When is it too late to plant grass seed?

Warm-season grasses must be planted at least two months before the risk of frost in warmer climates and three months in cooler climates, according to The University of Massachusetts Amherst Center for Agriculture. Cool-season grasses must be planted before the daytime temperatures lower to an average of 55 degrees Fahrenheit.

Planting grass too late in the season does not necessarily mean that the grass won't grow, but frost can damage or kill young seedlings, even those of cool-season grasses. Therefore, it is always best to plant grass at the ideal time for the climate and the specific species of grass being planted so that the plants have plenty of time to gather nutrients to survive the winter.