If you do one thing for a tired lawn, do this, and do it in early fall.
Why September
Soil is still warm so seed germinates fast. Nights are cooler, moisture is more reliable, and the weeds that outcompete seed in spring are winding down.
What aeration does
Hollow tines pull plugs out of the soil, creating real space for air, water and seed. Spiking compresses instead, which on clay makes things worse.
Leave the cores
They look untidy for a week and then break down, returning soil and microbes to the surface. Raking them up throws away part of the benefit.
Seed to soil contact
Overseeding straight after aeration drops seed into the holes, which is exactly where it needs to be. Broadcasting onto an unaerated lawn mostly feeds birds.
Then feed
Fall fertilizer after aeration is the single most valuable application of the year. It goes into root mass, which is what decides next summer.
Read next
Spring checklist for a GTA property
Eleven things to do between the thaw and the first cut, in the order that matters.
ReadFall checklist: what to do before the ground freezes
Nine jobs in October and November that are cheap now and expensive in May.
ReadHow winter damages hardscape, and how to prevent it
Plow shoes, salt, snow piles and the spring repair bill nobody budgets for.
ReadFree estimate
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