How to Repair Grub Damage

Before repairing, make sure the grubs are gone. If you applied a curative product, wait 2 weeks, then peel back a section at the edge of the damage and check. If you still see live grubs (more than 2 per sq ft), retreat before repairing. Seeding over active grubs wastes money because the new roots will be eaten too.

Use a stiff garden rake or power rake to remove all dead grass, thatch, and loose material from the damaged areas. You should see bare soil when you're done. Don't worry about being aggressive: the grass in these areas is dead and won't recover. Removing it gives new seed direct soil contact.

Use a garden rake or core aerator to loosen the top 0.5 to 1 inch of soil in the bare areas. Grub-damaged soil is often compacted from the disruption. Loose soil allows seed roots to penetrate. If the damaged area is large (over 100 sq ft), rent a slit seeder which cuts grooves and drops seed in one pass.

These are bare patches, not thin areas, so use the full new-lawn seeding rate: 6 to 8 lbs per 1,000 sq ft for tall fescue, 2 to 3 lbs for Kentucky bluegrass, 1 to 2 lbs for bermuda. Apply starter fertilizer (high phosphorus, like 10-18-10) at the same time. Phosphorus promotes root growth, which is exactly what new seedlings need.

Keep the seeded areas moist (not soaked) for 2 to 3 weeks. Water 2 to 3 times per day for 5 to 10 minutes each session. The top inch of soil should stay consistently damp. After germination (7 to 21 days depending on species), reduce frequency and increase depth to encourage root growth.

Set a calendar reminder for May to apply preventive grub control (GrubEx or equivalent). The newly repaired areas are the most vulnerable spots because the turf is young and thin. One more grub cycle will destroy the repair. Annual prevention costs $15 per 5,000 sq ft and eliminates the risk.