What you do between Labor Day and Thanksgiving decides more about next year's lawn than anything you'll do next spring. Here's the checklist we run on Treasure Valley lawns every fall.
1. Early-fall feeding (September)
The heaviest application of the year goes down while soil is warm and the lawn is rebuilding. Why fall feeding matters →
2. Core aeration (September–October)
Relieve a summer's worth of compaction so water and nutrients actually reach roots. Overseed thin areas while the aeration holes are open.
3. Keep mowing — and drop the height for the last cut
Mow as long as the grass grows. For the final mow of the year, take it down a notch (around 2 inches). Shorter winter turf resists snow mold and matting under wet leaves.
4. Don't let leaves sit
A thick mat of wet leaves smothers turf and breeds disease. Mulch-mow light leaf cover back into the lawn — it's free organic matter — and rake or blow heavy cover.
5. Blow out the sprinklers (October)
Treasure Valley winters will crack any line left holding water. Schedule the blowout after the lawn no longer needs irrigation but before the first hard freeze. Our shutdown timing guide →
6. Winterizer (late October–November)
The final feeding banks nutrients in the roots for an early, thick spring green-up. How winterizer works →
Program customers get items 1, 2, and 6 handled automatically — see the full program.
Frequently asked questions
What should I do to my lawn before winter in Idaho?
Six things: the early-fall feeding, core aeration, keeping leaves cleared, lowering the final mowing height slightly, shutting off and blowing out sprinklers before a hard freeze, and applying a late-fall winterizer.
How short should I cut my lawn for winter?
Drop the final cut or two slightly below your summer height, but don't scalp it. Grass left long mats under snow and invites disease; grass cut too short loses the insulation and food reserves it needs to survive winter.
Do leaves really hurt the lawn?
A thick mat does. It blocks light and traps moisture against the crown, which encourages disease over winter. A thin scattering mulched in with the mower is fine and returns organic matter to the soil.