Don’t waste time and money
Spring weather and lawn improvement seem to go hand in hand.
But for over 40 years, I've been recommending to clients that Fall is best for lawn seeding (September here in Pennsylvania).
For some reason, Fall seeding runs counter to all those natural urges, probably carried over from prehistoric cavelawn days.
Lawn jocks just can't fight off that spring lawn care urge, getting back to their roots and all that other earthy cavelawn stuff.
Besides all the logical reasons for seeding a lawn in the Fall, there is one excellent reason NOT to seed in the Spring.
If you, or your commercial lawn care service, are applying pre-emergent herbicide (that's the long name for crabgrass control) chances are your newly planted grass seed will fail.
The technical term in the landscape industry is a "seeding failure."
Why does that happen?
Crabgrass controls have been developed to keep crabgrass seeds from germinating, or more precisely, designed to chemically 'nip' young roots as they emerge from the germinating seed. With 90% of the pre-emergent "Step One" lawn care products on the market, that exact same thing will happen to your germinating grass seed, the stuff you just used hard earned dollars to purchase. Your young grass roots will get nipped and your grass seed won't grow.
While older grass roots like these aren't usually
affected, newly emerging grass roots get
"nipped" by pre-emergent herbicides
If you are still dead set on applying a crabgrass control AND seeding your lawn, you will find one or two products on the market that will work. But most of the standard pre-emergent herbicides stay active in your lawn soil for 1 to 3 months, so any grass seed planted during that time period is at great risk of failure.
A much more logical sequence is:
1. Control crabgrass in the spring,
2. Control broadleaf weeds in early summer,
3. Seed your lawn in the Fall.