There are several reasons Kentucky bluegrass and tall fescue lawns are better seeded in the fall than in the spring. These include:
– Some of the most serious lawn weeds such as crabgrass and foxtail emerge in the spring. Since they are warm-season weeds, they will compete and often crowd out young, tender cool-season grasses during the heat of summer.
– The most stressful time of year for cool-season grasses is summer, not winter. Poorly established lawns may die out during the summer due to heat and drought stress.
– A lawn often gets more use during the summer, leading to increased compaction and traffic stress.
If an area needs to be established in the spring, sodding is much more likely to be successful than seeding. Sodding provides stronger, more mature plants that are better able to withstand stress and prevent weed invasion. (Ward Upham)