Seeding After Pre-Emergent Application: What to Expect

The Conflict

Homeowner aerated, applied granular pre-emergent, watered, then raked. Now wants to seed, topdress, and mulch with hay. Asks how long to wait.

Hard Truth

Pre-emergents are designed to last 3–4 months. If they work perfectly, no grass seed will germinate this season. If they degrade fast, they didn't control weeds either.

Practical Compromise

Seed anyway—some will establish despite residual herbicide. Expect reduced germination and some weed breakthrough. This is the "least bad" option.

Better Strategy for Next Year

1. Fall seeding – Cool season, less weed pressure.
2. Spring pre-emergent – Apply after new grass is established (3–4 mowings).
3. Sequence – Grow grass first, prevent weeds second.

Memphis Timing

Fall (Sept–Oct) is ideal for tall fescue. Spring seeding battles crabgrass and heat stress.