Cultivation
Fall overseeding (cool-season)
Spreading new seed in early fall fills thin spots while soil is still warm enough for fast germination but air is cool enough that the seedlings outpace summer weeds. Fall overseeding establishes a thicker stand than spring overseeding and avoids competition with crabgrass.
Either/or: Either this or Fall pre-emergent (Poa annua), not both this season: a pre-emergent blocks new grass seed for about 12 weeks.
Conditions are close to the action band. Monitor daily, the window typically opens within a few days.
How to decide
A fall pre-emergent blocks new grass seed for the length of its reseeding restriction, which spans the whole fall seeding window. Extension guidance leans toward seeding on a cool-season lawn, since a dense new stand is itself the best long-term poa annua defense. Mesotrione (Tenacity) tolerates cool-season seed but is not a poa annua program on its own.
Read how to decide →