Overseeding Fescue on Clay: Aeration, Slit-Seeding, and Amendments

Recommended Sequence

1. Mow low (1–2 inches).
2. Core aerate (hollow tines).
3. Rake up cores (clay plugs smother seed if left wet).
4. Slit-seed (best seed-to-soil contact) or broadcast seed + drag mat.
5. Starter fertilizer (3 lbs/1,000 sq ft).
6. Pelletized lime if soil test indicates (pH <6.5).
7. Winterize in 4–6 weeks (28-3-14).

Gypsum? Only If Sodium Is High

Gypsum only helps sodic (high sodium) clay. Test first. Tilling in large amounts works; surface dusting doesn't.

Better Than Gypsum: Compost Topdressing

After aeration, spread ¼–½ inch compost. Expensive but transforms clay biology. If budget tight, skip—organic program (sugar, meals) builds biology over time.

Seed & Fertilizer Rates

• Overseeding: 3–5 lbs fescue/1,000 sq ft.
• Fertilizer: 3 lbs/1,000 sq ft (standard lawn fertilizer).

Watering Critical

Keep soil surface constantly damp until germination. Multiple light cycles daily.